>> reporter: nearly thirty years. sixty investigators. and it all kept coming back to one elusive suspect. >> he just very calmly said, "i know how to get rid of a body so it would never, ever be found." >> to him, i think, murder is something that can be done over a lunch hour. >> we were just a heartbeat away from not having a case. it was basically a now or never situation. >> hello and welcome to date lain. when kathy heckel disappeared police didn't know if they were dealing with a missing person case or cold-blooded murder. with little evidence to go on, the investigation grew cold. decades later a young detective who was just a kid when kathy vanished dusted off the old files. investigators couldn't solve her case then. could he help solve it now here's josh mankiewicz with "she didn't come home." >> reporter: time can be like a river. a long stream of events rushing by. most barely make a ripple. but a few, like the sudden loss of a close friend, a child, or a parent, have a way of circling back upon us in a ceaseless loop of memory and regret. that's the way it's been for john heckel and his sister alicia talbot ever since that completely normal morning in 1991 when their mom, kathy heckel, kissed them goodbye, left for work and never returned. >> you -- you remember her leaving that morning? >> yeah. i -- i mean like every other day. >> yeah. >> same routine all the time, every time she left us, she kissed us goodbye. >> reporter: it was a july morning. alicia, 13, and john, then nine, were home for summer vacation. a little after 9:00 a.m., alicia says her mom called from her job. >> we discussed having dinner and having pork chops. >> uh-huh. yeah. 'cause that was one of my favorite things she cooked. >> reporter: later, they tried to contact their mom at work. >> one of the times we tried to call her was around lunchtime. and she had left for lunch. >> yeah. >> and then we waited and called after lunch, and she still wasn't back to work yet. >> reporter: at 40, kathy heckel had spent half her life working at the local paper plant in lock haven, pennsylvania. >> i can't remember who i was speaking to at the office. but you could hear in their voice that there was some concern there that she hadn't come back yet. >> and you picked that up. >> yeah. it was not typical for her to not come back and not tell anybody. >> reporter: with their dad out of town, they kept trying to reach their mom. nothing. at about 6:30 that evening, alicia called her grandparents, clarence and margaret dolan. >> i answered the phone. it was alicia. she said, "gram, can you get us some milk?" and i said, "what -- what do you mean, can i get ya some milk?" she says, "well, mom didn't come home yet," and she says, "we don't have any milk. and i said, "alicia, i will be right there." >> and you're thinking what? >> i didn't know what to think. but as a mother, you know that this is something bad, something very bad. >> reporter: that night, kathy's mother and father contacted everyone they could think of. >> no one had heard from her. and that was -- i remember picking up on that, that they seemed -- they seemed worried. >> i mean you could just tell. >> your grandparents were acting differently? >> uh-huh. >> uh-huh. >> reporter: their dad, john, was in upstate new york that monday training with his national guard unit. he didn't learn his wife was missing until the next day. >> you get that phone call. it's your mom. >> yeah. >> what'd she say? >> the gist of the conversation was that kathy didn't come home from work on monday night. and they didn't know where she was. >> and now it's tuesday. >> and now it's tuesday evening. >> and you think what? >> i said, "time to call the state police." >> reporter: with the permission of his commanding officer, john heckel immediately left for home. he had plenty of time to think on that five and half hour ride. he thought about the time kathy donated a kidney to save her brother's life and about the december day in 1972 when he first gazed at kathy dolan. >> she just had the biggest brown eyes you could look into. >> reporter: six months later, they were married. >> like any marriage, i think we had our ups and downs. but overall, i was -- i was happy about the fact i didn't have to worry about my family with kathy. >> you thought you were gonna stay married forever? yes. >> reporter: the problem was, john was already married to the military. john's career frequently took him away from home. sometimes for weeks at a time. kathy didn't like that. and john says his wife of eighteen years seemed to have that on her mind when she'd dropped him off for his latest guard assignment. >> she asked me why i had to be there so early, which didn't make sense to me because i was always the first one there. and i said, "it's my job." >> she didn't want you to go? >> she didn't say "i don't want you to go." >> but you felt it. >> i could feel that something was wrong. the look on her face when she said it, it's -- it just didn't set right with me. >> reporter: now kathy was missing and her disappearance would eventually drag into the open secrets that some in and around lock haven would have rather kept hidden. >> there was no doubt kathy took good care of her family. but as investigators soon learned this wife and mother was also a woman who was sometimes lonely. coming up -- >> i asked her mom if she was seeing anyone. and she said that she had re-established contact with an old friend from school. >> and that old friend had a confession to make. >> he did admit that they had had a physical relationship. and it had only been a few days before she disappeared. >> when dateline continues. whes ♪ since pioneering the suv in 1935, the chevy suburban has carried many things. nothing more important than family. introducing the most versatile and advanced chevy suburban and tahoe ever. who've got their eczema under control. with less eczema, you can show more skin. so roll up those sleeves. and help heal your skin from within with dupixent. dupixent is the first treatment of its kind that continuously treats moderate-to-severe eczema, or atopic dermatitis, even between flare ups. dupixent is a biologic, and not a cream or steroid. many people taking dupixent saw clear or almost clear skin, and, had significantly less itch. don't use if you're allergic to dupixent. serious allergic reactions can occur, including anaphylaxis, which is severe. tell your doctor about new or worsening eye problems, such as eye pain or vision changes, or a parasitic infection. if you take asthma medicines, don't change or stop them without talking to your doctor. so help heal your skin from within, and talk to your eczema specialist about dupixent. if your financial situation has changed, we may be able to help. just one jar of olay regenerist has changed, has 4x more hydrating power than the $400 cream. for skin results you'll see, or your money back. olay. face anything. for even more hydration, try olay serums. special guest flo challenges the hand models to show off the ease of comparing rates with progressive's home quote explorer. international hand model jon-jon gets personal. your wayward pinky is grotesque. then a high stakes patty-cake battle royale ends in triumph. you have the upper hands! it's a race to the lowest rate, and so much more. only on "the upper hands." it's a race to the lowest rate, and so much more. it's just a cold. if you have high blood pressure, a cold is not just a cold. most cold medicines may raise blood pressure. choose coricidin hbp. the brand with a heart. for powerful cold relief without raising your blood pressure. you ready for this? 'cause we're all set. so let's woah. ready. set. woah. universal orlando resort. buy two days and get three days free at the parks. restrictions apply. >> reporter: by the time john heckel returned home from national guard training in new york state, his wife kathy had been missing for about 36 hours. >> when my dad came back, he was the one who told us, "we can't find your mom. we don't know where your mom is." and that was the first time i've ever seen my dad cry. and i -- i knew the worst had definitely happened if he was that worried. >> and that was the first time i saw my dad cry, too. and, you know, he was always this big, strong man. and -- and when you see that, you -- it's like, "okay, this is -- this is not good." >> reporter: that's gotta be a terrible thing to tell your kids. 'cause they want -- they want you to tell them, "this is gonna be okay." >> dad always had all the answers. >> and you can't tell them this is gonna be okay. >> no. you don't want fabrication. >> reporter: across town that morning, pennsylvania state trooper fred caldwell was on the case. his first call had been to margaret dolan, kathy's mom. >> i remember asking her if she had noticed any changes recently or anything in her demeanor that was unusual. and she said that in the last four to six weeks or so, she just wasn't herself. >> reporter: then the trooper asked one of those probing, indelicate questions that cops have to ask. >> i asked her mom if she had any indication that she was seeing anyone. and she said that she had reestablished contact with an old acquaintance, an old friend from school. >> that man's name was dennis taylor. he and kathy had recently reconnected at a wedding. taylor had been singing and playing guitar. the trooper jotted down the name dennis taylor with the idea of calling him later. next he dialed the paper plant where kathy was last seen. one of kathy's co-workers picked up the phone. >> she kinda corroborated what her mom had said, that she'd been a little different in the last few weeks, personality just seemed a little quieter maybe. >> reporter: then he asked question number two. >> i also asked her if she felt that there was a possibility that she may have been having an affair or seeing anyone. and she said she had no evidence but she suspected that she may have been. >> the co-worker wasn't talking about kathy's friend, dennis taylor. she was talking about a man at the plant named loyd groves. >> they both played on the same volleyball team. they spent some time after hours together. and i think just the closeness of the two and she just kinda suspected that they may be. >> reporter: the trooper learned groves was the quiet type. married with children. sometimes he led plant tours and gave paper-making presentations to local schools. a call to grove's office revealed he wasn't in yet. so the trooper left a call back message. and not long after, the trooper says mr. groves showed up in person at the state police barracks. >> he was very calm. he said that he knew her. they share -- they worked in the same office areas. he said they were friends. i did ask him if he had any type of physical relationship with her and he said no. >> reporter: shortly after loyd groves left the state police barracks, the other man on trooper caldwell's list walked in. dennis taylor, the guitar man. like groves, taylor was married man with children. and right off the bat, he told the trooper he had a confession to make. >> he did admit that they had had a physical relationship briefly. and it had only been a few days before she disappeared, as i recall, the first contact, physical contact. >> reporter: like a balladeer who knows his audience is hanging on every lyric, the guitar man kept singing to the cops. taylor told the trooper kathy heckel had called him at work the day she disappeared. her voice, he said, had a strange tone. >> she called him just before lunchtime and was upset or anxious and said that she had something she wanted to talk to him about. and he was busy. and he said, "i can't talk. i'll call you back," and hung up. he did try to call back then sometime later. and she had gone for lunch. >> reporter: taylor said he'd played golf with friends that afternoon and had planned to meet up with kathy later that night. >> denny goes to their location where they're gonna meet. kathy doesn't show up. he was concerned that something may have happened. >> reporter: it was then the guitar man struck a familiar chord. kathy heckel, he said, had also been seeing another man. a guy named loyd groves. according to taylor, this fellow groves was a bit of a stalker. >> he said that he had met kathy at a park, a nearby park. he said that there was a gray van parked nearby. he recalled seeing the van. and the next time he talked to kathy she said, "did you see that van? that was loyd." and he was following her. >> reporter: was the guitar man being helpful, or was he trying to implicate a rival to save his own skin? the trooper knew this much. if kathy heckel had been juggling simultaneous affairs with married men, there could be a lot of people who wanted her to disappear including her husband. >> he was definitely a person of interest. >> reporter: exactly how much did john heckel know about what was going on in his wife's life? >> coming up -- were police looking for a runaway wife or her killer? >> there were just no answers. and that was -- that was the worst part. >> did you feel like you were ever a suspect? >> never worried about it. i knew they would try to find where kathy was and what had happened, and if that included questioning me i had no problems with that. >> when dateline continues. tha. >> when dateline continues >> reporter: any investigation in which someone goes missing or turns up dead -- just about guarantees family members will be considered suspects. kathy heckel's husband john was no exception. >> we did consider that john may have known that his wife was having an affair and that he may have taken some action on his own. >> did you feel like you were ever a suspect? >> never worried about it. i knew they were tryin' to find where kathy was and what had happened. and if that included questioning me, i have no problems with that. >> at some point somebody said to you, "we believe she was having a relationship with some other people." was that shocking to hear? >> it was surprising, because that wasn't the way kathy was. >> reporter: in his interview with trooper caldwell, john heckel said he'd noticed a change in his wife's demeanor in recent weeks and wondered if she might be having an affair. >> he was emotional. there's times when john and i just sat together with my arm around him and he would cry. he was concerned about his wife. and i felt very bad for the man. >> reporter: john heckel's alibi checked out. and police found no evidence he'd paid anyone to hurt his wife. by now, kathy had been missing for two full days and john heckel feared the worst. >> kathy heckel would never on this earth abandon those two children. >> reporter: trooper caldwell still didn't know if he was working a missing persons case, an abduction or a homicide. then on the evening of the third day investigators got a big break. they found kathy heckel's car parked behind the local hospital. the keys were missing. >> i think they recovered one print. but i don't know that it was ever identified. it was from the exterior of the car. >> reporter: investigators were now pretty sure that someone, possibly her killer, had moved kathy heckel's car to the hospital parking lot. and then the case hit a dead end. days turned to weeks. those weeks stretched into months. kathy heckel was somewhere in the wind. >> we had cadaver dogs come down often. and we would have troopers go out and we would search the area looking for remains or whatever. >> reporter: while some investigators focused on finding kathy heckel, others concentrated on finding evidence of a crime. as far as investigators could tell, the guitar man, dennis taylor, had been honest, confessing his affair with kathy heckel. loyd groves, on the other hand, had seemed a bit dodgy. troopers had searched loyd groves home office and van. and while some items of interest were found, the local prosecutor didn't think police had enough to make an arrest. >> there was a big hole from an investigative standpoint. >> reporter: ted mcknight was clinton county district attorney at the time. >> if you can imagine a yardstick, and probable cause is probably at the two inch mark, and beyond a reasonable doubt is probably at the 34 inch mark. and everything else in between is the difference between are you gonna get a conviction or aren't ya. >> which means you don't go forward unless you're reasonably sure you have the evidence for a conviction. >> correct. >> reporter: he says the fact that kathy heckel's body had not been found was a big problem. >> how do we prove beyond a reasonable doubt that she is dead? if she was killed, where did the killing occur? what county did it occur in? >> maybe it's not even your jurisdiction? >> correct. >> reporter: for the heckel family, kathy's disappearance was a defining event. >> i remember being depressed. i didn't know what that meant when i was nine years old. but just thinking about how low and sad i felt all of the time. >> i think people deal with things differently. and i certainly chose, i think, the avoidance method. >> not think about it. >> and not think about it. >> there were just no answers. and that was -- that was the worst part. >> reporter: in 1998, seven years after kathy disappeared, john heckel had his wife declared legally dead. that did not make the mystery any easier for him to understand. >> can you accept the idea that, maybe, there were needs that she felt that she had to meet with men who were not you? but that she still loved you. >> oh, no. i believe she did love me. >> she had a secret life that she wasn't showin' anybody else. >> but you don't know how long that secret life was, and neither do i. it could have been her plan to wanna end that the day when she asked me why i had to leave so early. i don't know. but i'm not gonna hate her for being human. >> do you blame yourself? >> little bit. >> reporter: 22 summers came and went. john heckel remarried. the kids grew up. they started new lives out west. alicia became a ski pro, john, a fishing guide. but through it all, their mother was never far from their thoughts. >> she missed all those childhood memories. i mean things like going to the prom, and boyfriends, and kisses and just -- just everything. >> yeah, she missed our weddings. i mean she missed our graduations. she doesn't know her only grandchild. >> and you probably thought about her at each one of those. >> mm-hmm. >> mm-hmm. >> reporter: clinton county never forgot kathy heckel either. she'd become a part of history that just wouldn't go away. and as one generation of lawmen retired, another rose to take up the unfinished business and discovered enticing details buried in a very old file. >> coming up -- >> when i came to this case it was 22 years old. >> and it had passed through other hands. >> 68 investigators. >> he was 8 when kathy disappeared. now he was in charge of her case. >> what i remember growing up is where was she? where was kathy at during all this time? >> and a leading suspect suddenly leaves town. >> about 3 weeks after the disappearance of kathy he moved his family back. >> when dateline continues. s fa. >> when dateline continues this is time that matters. a window of time to help protect the ones you love. your preteen benefits from staying up-to-date with their well visits. this is your window of protection. schedule their well visit now. for skin as alive as you are... don't settle for silver ♪ gold bond champion your skin ♪ ♪ heart monitors that let your doctor watch over you, just like you watch over your best friend. another life-changing technology from abbott, so you don't wait for life. you live it. hello. i'm dara brown. here's what's happening. hundreds of thousands of people are without power after hurricane delta made landfall friday night as a category 2 storm with maximum sustained winds of 100 miles an hour. it's the 12th storm to strike the lower 48 states this year. more than a foot of rain was reported in lake charles and record amounts of rain reported in other parts of louisiana. now back to dateline. welcome back to dateline. i'm natalie morales. investigators suspected kathy heckel may have been murred. but with no body and little evidence the case went into a deep freeze for decades. kathy's family had never been able to sake the chill of their inconceivable loss. but now a new detective was about to turn up the heat. here again is josh mankiewicz with "she didn't come home." >> reporter: for more than twenty years, kathy heckel's children lived with a feeling of unfocused fear. >> it's an unsettling feeling that -- an unsettling feeling of fear that essentially something great in my life can be taken away at any moment. >> and you think that can all be traced back to your mom? >> absolutely. >> absolutely, yeah. >> reporter: for their father john, those were years spent struggling to let go and move on. >> i talked to kathy a lot about it. >> what do you say to her? >> just talk, just ramble on. >> and you just start talking to her out loud? >> yeah. something'll come up that'll remind me of something we did. >> reporter: law enforcement had not forgotten kathy heckel. in the summer of 2013, a native son inherited the case, state police investigator curtis confer. >> when i obtained this case, it was 22 years old. >> and it had passed through a lot of other hands. >> 60 other investigators. >> 60? >> 60. >> and you thought i'm gonna close it or in a little while there's going to be a 62nd. >> well, josh, what was interesting was it was 400 pages of reports, and i just read it. >> reporter: to this 61st investigator, the reports were riveting. he'd heard the story as a child, and even had a connection to loyd groves, whose name was all over that file. >> he came to my elementary school and did a presentation on making paper. >> you saw a photo of him giving these -- >> yeah. and i went, you know what? i remember him doing our school. >> reporter: confer was now convinced that at the time this picture was taken, loyd groves was having an affair with kathy heckel. only two months later, investigators considered groves a suspect in her disappearance. >> what i remember growing up is where was she? where was kathy at during all of this time. john heckel was my brother's soccer coach. >> reporter: the case files were chock full of details. a gun found in loyd groves desk drawer. ammo found in his van. a curious chunk of carpet missing from the back of the van. >> what was loyd's explanation for cutting the carpet out of the van? >> in 1991, he said that the kids were playing with tar and oil and they got tar and oil in that section of the van. >> that confirmed by anybody? >> no, it was not. >> reporter: that wasn't the only thing to jump off the page. the original investigators had a witness who'd reported seeing kathy heckel and loyd groves together in his parked van many times in the weeks before she disappeared. and there was evidence that on the day kathy heckel never returned from lunch, loyd came back so late he missed a 2:00 p.m. meeting. >> something that the original investigators found was that loyd groves wrote a letter to his wife, announcing to the family that he was going to be arrested for the murder of kathy heckel. >> this is right after the disappearance? >> this is right after the disappearance, and he wrote detailed notes to his wife on how to take care of the tractor, how to take care of the car. >> this is a guy who likes to plan. >> he is a planner, yes, meticulous. >> but he's not arrested. he was wrong. >> yeah, he was not arrested. about three weeks after the disappearance of kathy, he moved his family back to beaver, pa, and then eventually selling his home, leaving -- leaving a lot of his personal items at his home. >> reporter: when he finished reading the case file, confer called the local fbi office looking for some items connected to the case. it was then that he connected with mike hutson, a veteran state trooper assigned to a joint terrorism task force. after confer explained what he was after, hutson asked to see the file. >> i thought it was a very good case. i felt that there was, you know, a very real suspect. >> reporter: when hutson's partner, fbi agent and former prosecutor kyle moore read the file, he too was hooked. >> this is something we wanted to do something about. we wanted to see if there was any way that, you know, we could actually bring it to a conclusion. >> reporter: so within days of getting the case, investigator number 61 had a team to help him. >> they had so much knowledge that i didn't have, it was by the grace of god that they helped me with this case. >> reporter: time, it became clear, was not on their side. >> it was basically a now-or-never situation, and i always felt we were just a heartbeat away from losing a witness, to not having a case. >> reporter: as they worked the case the investigators knew they had one ace in the hole. in 1991, specks of blood had been found in loyd groves' van. advanced dna tests were done in 2004. >> based off the fact that there wasn't a dna sample from the victim, they essentially had to construct one from the victim's mother and father, essentially building the victim's dna profile. >> reporter: that dna test proved the blood was kathy heckel's, but trooper confer says it seems that bit of evidence fell through the cracks because the lead investigator and primary prosecutor at the time took medical leave. one thing was clear to all three of the new investigators, this case needed more resources and more prosecutorial muscle than clinton county possessed. >> we requested that the district attorney relinquish the case to the attorney general's office, and the d.a. at the time agreed. >> reporter: in early 2014 a grand jury was empaneled to review the evidence. hutson, moore and confer hit the road. >> so we did interviews in different states, and traveled the country a little bit. >> reporter: the new investigators tracked down old witnesses and even found a new one. a man who remembered an argument between kathy heckel and loyd groves on the day she went missing. the question was did police have enough to make an arrest? 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>> yeah, he told his son that he needed to get a different ride to work. >> so -- >> it really didn't faze him. >> reporter: and behold, loyd groves is arrested. what was that like to hear? >> inner-thankfulness that we were getting somewhere. >> still a long way to go. >> yeah. still a long way to go. >> reporter: in many ways, the arrest of 65-year-old loyd groves was the easy part. legal maneuvering delayed his trial another three and a half years. for the defense, the delay gave their investigators time to poke holes in the prosecution's case. >> this case had holes you could drive trucks through. >> reporter: tom bruno and his wife, amy, were the defense team's investigators. >> we were in the case for nearly four years. we actually talked about him, i would guarantee every day. >> reporter: tom, a former cop, knew how to look for flaws in the police work. amy, a lock haven native, had grown up with the kathy heckel story. >> you talk to anyone in town, they would all say that loyd killed her and he put her in a vat of acid and dissolved her body. that was the working theory for years. >> reporter: but tom says the files he read didn't prove any of that. in fact, he says he found a silver bullet in those piles of documents. >> we actually discovered that in the police reports, in medical records, that she had cut her finger at work. it was bleeding so badly that she had to get it treated three times. and this was at the time that she was allegedly in her -- in loyd's van every day. >> reporter: so if the prosecution planned to make a big deal out of a dna test showing kathy heckel's blood in loyd groves' van, the defense response now would be so what. >> they think it came from kathy because loyd killed her. but yet, here's kathy's blood because she cut herself at work. >> i mean, if this isn't reasonable doubt, what is? >> reporter: as the case went to trial in november, 2018, pennsylvania senior deputy attorney general daniel dye knew the defense would do more than just attack their evidence. he feared they would attack kathy heckel too. >> i got to know this family. i worried a lot about them because i knew this would be an ugly trial. >> and that every single indiscretion of hers was going to be announced in open court? >> she was going to be punished for being murdered. >> reporter: the prosecution's case, almost entirely circumstantial, began with testimony from kathy heckel's children. >> it was a little difficult. but it felt good to be in front of loyd groves and have him look at me and listen to my story. >> and how scary it was? >> uh-huh. >> uh-huh. >> reporter: according to friends and family, kathy heckel was a devoted daughter, a loving mom. at the same time, she was also restless. >> tell me what was going on in her life at that time? >> her life at that time was a lonely life. john heckel is a good guy. but his first love was the military. and kathy was, you know, having affairs and one of them was with loyd groves. >> reporter: another lover, the guitar man, dennis taylor, said kathy had told him all about that unraveling affair. >> kathy was trying to break off the relationship. we know that. loyd did not want the relationship to end. and he specifically wanted to meet for lunch on that day. >> did loyd groves know about denny taylor? >> he did. we had evidence in the case that -- that groves was following kathy. >> taylor testified that kathy had expressed some fear about loyd? >> right. >> in a special hearing, two former paper plant employees who'd been in poor health had their trial testimony pre recorded. one said he'd overheard kathy heckel and loyd groves arguing the day kathy went missing. >> just loud. >> reporter: the other said she saw loyd groves staring daggers at kathy heckel as she left for lunch that day. >> his face was so red, just like he was terribly angry. he was looking at kathy. >> kathy pulls out. loyd pulls out after. we believe that they did meet. that somehow, some way, kathy was cajoled into one last meet just to hear loyd out. and at that point in time, loyd shot her, shoved her in that van, likely with a head wound. >> reporter: according to witnesses, groves was back at the plant sometime between 2:00 and 3:00 that afternoon. >> you think loyd groves kills her, disposes of her body, and manages to get back to work that day and act like nothing's wrong and get away with it? >> i think it's because he's smart and a good planner. to him, i think, murder is something that can be done over a lunch hour. >> reporter: the prosecution wrapped up its case with two witnesses, people who only surfaced shortly before trial. the first was loyd groves' now ex-wife. >> there was something she had been holding back on telling for the past roughly 30 years. and that was that loyd groves did come home over the work hour on july 15th, 1991. >> something he almost never did? >> which he never did and changed out of his clothes. and she never saw the condition that those clothes were in. >> reporter: the next person to testify was this woman, gayle taylor. she also had a story to tell that she'd kept to herself for decades. it was the mid-'90s. taylor said that she and groves worked together in ohio. according to taylor, she went to groves one day to vent after she'd discovered drugs in her son's room. >> i was like, "i don't know what i'm gonna do with this kid. he's gonna get into trouble. he's gonna end up dying. if he -- if -- if the drugs don't kill him, his mother will." and loyd was sitting at his desk and he just very calmly said, "well, i know how to get rid of a body so it would never, ever be found." >> the defense's argument was he was joking? >> i sure wouldn't joke about being able to dispose of a body where no one could ever find it, if i had been investigated for killing somebody and they had never found the body. >> reporter: the prosecution closed its case by asking who but loyd groves could have killed kathy heckel? and in return, the defense stood ready to ask a provocative question of its own. could kathy heckel have simply run away? >> coming up -- >> did you really think she lived past that day? >> i certainly have a reasonable doubt as to whether she died that day. >> would the jury have the same doubt? >> it was a nervous moment, absolutely. >> when dateline continues. >> when dateline continues want the cream winning beauty's best? just one jar was named best retinol cream, best retinol moisturizer, and best overall night cream. olay retinol24 faced the test to be awarded the best. olay. face anything. who knows where that button is? i don't have silent. everyone does -- right up here. it happens to all of us. we buy a new home, and we turn into our parents. what i do is help new homeowners overcome this. what is that, an adjustable spanner? 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maybe you think... it's occasional constipation. maybe it's not. it could be a chronic medical condition called ibs-c, and time to say yesss! to linzess. linzess works differently than laxatives. it helps relieve belly pain and lets you have more frequent and complete bowel movements. do not give linzess to children less than six and it should not be given to children six to less than 18, it may harm them. do not take linzess if you have a bowel blockage. get immediate help if you develop unusual or severe stomach pain, especially with bloody or black stools. the most common side effect is diarrhea, sometimes severe. if it's severe, stop taking linzess and call your doctor right away. other side effects include gas, stomach area pain, and swelling. change your thinking to ibs-c. if your constipation and belly pain keeps coming back, tell your doctor and say yesss! to linzess. welcome back. decades after kathy heckel disappeared lloyd grove was on trial for her murder. prosecutors relied largely on circumstance substantial evidence to make their case including testimony from a woman who said lloyd told her he could get rid of a body permanently. but lloyd's attorneys insisted he was innocent and were ready to put kathy's love life in the spotlight to prove it. here's josh mankiewicz with the conclusion of "she didn't come home." >> reporter: the loyd groves defense team could hardly wait to make their case to the jury. >> it was like you're playing cards. and you have four aces. and you're waiting to play 'em. that's what we felt like over the last few years. >> reporter: george lepley was one of two lawyers defending groves. >> i don't think there was enough evidence. and what evidence they did present had issues questioning whether it was reliable enough to justify taking the rest of a man's life away. >> reporter: for a defense team that had spent years reviewing police reports, one thing seemed obvious. >> when the police learned of something that implicated loyd, they were on top of it. whenever there was another avenue to pursue, it just kinda falls by the wayside. >> this was more about the police trying to prove that it was loyd groves that did this crime than it was about them trying to find out who killed kathy heckel. if indeed she was killed. >> reporter: the defense argued the guitar man, dennis taylor, should have gotten a closer look. >> yes, she had an affair with loyd. but she also was having an affair with dennis taylor. >> reporter: taylor had told the police that he played golf the afternoon kathy heckel went missing. >> they went to check his alibi out, 13 months later. not right away. and when they go there, a log that he has to write in to show that he was golfing there, the pages are missing. isn't that convenient? >> reporter: and of course the defense argued, kathy heckel's affairs could have also provided her husband with a motive for murder. weeks after kathy heckel disappeared, the defense noted, john heckel discarded some of her personal items. >> her husband throws away her purse, her wallet, her -- her photo id. it isn't that he throws it in a garbage can in front of his house where somebody might see it. it's in a dumpster in the back of the reserve base. >> you're saying that he wanted to conceal that? >> what more logical conclusion is there? >> reporter: did john heckel have something to hide? the defense didn't offer an answer for that and john heckel says he doesn't remember much about those days. >> i don't recollect throwing anything like that out. >> reporter: the defense even suggested that kathy heckel may not have died on july 15, 1991. >> did you really think she lived past that day? >> i certainly have a reasonable doubt as to whether she died that day. >> reporter: to support that theory the defense introduced statements john heckel made more than 20 years ago. in one, heckel said he thought his wife may have siphoned thousands of dollars from a joint bank account. in another he asked investigators if a woman pictured in a swingers magazine might be his wife. >> reporter: is there any credible argument that kathy heckel squirreled away money, vanished, ran out on her husband and her family and then posed for pictures that were put in a swingers magazine that anybody could have seen? >> i certainly don't think it has been disproven beyond a reasonable doubt that that could have occurred. >> reporter: on the stand, john heckel said those decades old statements had been the frantic musings of a desperate man. >> i was grasping anything i could think of to try to find out what happened to my wife. >> reporter: the defense conceded, groves did go home that day to change his shirt but said that was because he'd gotten dirty at the plant where he had to lead a tour for a group of children at 3:00 that afternoon. and that lunch hour trip home, they argued, simply made the prosecution's version of events even more unlikely. >> if you factored in all of the witnesses when they saw him at the plant, how does he have anywhere near enough time for him to have done what they claim he did? >> reporter: for 27 years the question of what had happened to kathy heckel had hung over lock haven. now it was up to a clinton county jury to finally provide an answer. >> it was contentious. >> reporter: shaun sanford, a toddler at the time kathy heckel disappeared, was the jury foreman. >> the very first vote we took was 7-5, 8-4 for guilty. i thought it was gonna be the other way for acquittal. >> why did you vote for acquittal on that first vote? >> if you looked at every piece of evidence individually, you could poke holes in all of it piece by piece. >> reporter: after breaking for the weekend, the jury returned on monday morning rested, but still deadlocked. >> there was one juror in particular who was voting for acquittal originally, who couldn't get over the fact that he thought the prime suspect should be john heckel. >> reporter: over and over, jurors reviewed and discussed the evidence. then just before 3:00 that afternoon, jurors notified the judge they had reached a verdict. >> it was a nervous moment, absolutely. i -- i was nervous. and we were all holding hands. >> reporter: on the charge of first degree or premeditated murder, the verdict was "not guilty." then in what seemed to be a compromise decision, the jury found groves guilty of third degree murder which is legally considered a spontaneous act in the heat of the moment. >> you look at groves during that time? >> no, i spent more time looking at kathy's picture and crying. >> reporter: in a letter to "dateline," loyd groves once again denied ever having had an affair with kathy heckel and said he'd been wrongly convicted. at the age of 69 groves was formally sentenced to serve 10 to 20 years in prison. >> even with the third-degree sentencing, he'll still spend the rest of his life in prison. >> that's enough for you? >> uh-huh. >> uh-huh. >> reporter: it's been more than a quarter century since the summer morning when kathy heckel kissed her children goodbye. and although their wait for justice is finally over, they are still no closer to knowing where their mother is than they were on that summer night in 1991 when she didn't come home. >> so unless your mom's remains are found accidentally, you might not ever know? are you gonna be okay with that? >> we have to live with it. i -- i mean it's sad. and it's disappointing that we will never know, or we may never know, but we have to be okay with it. >> that's all for this edition of "dateline." i'm craig melvin. >> and i'm natalie mar allealos. >> and this is "dateline. ". >> it i was trying to see what she had on and he whispered and said, "red blood." chills up and down my spine because i thought, wow, this kid saw this. >> a little boy witnessed something terrifying the night his mother vanished. >> it just was ripping my heart. >> he was so traumatized. >> everybody's life changed that night.