check done on my daughter. >> a secret life and covered. >> she was looking for sugar daddies. >> going into it blindly is not something i would recommend. >> chilling details revealed. >> selected her as his victim? >> correct. the bottom of the dig site, there was a damaged iphone. maybe clothing, there was a sinking feeling, really. >> i replay this one night and i went to grab her and say do not do it. do not go. >> hello, and welcome to dateline. college student mackenzie lueck was diving into adulthood, eager to find her path. her family and friends knew her as fun, responsible, and always careful. then, one night she vanished. a trail of electronic clues helped investigators retrace our steps and exposed a dark underworld where evil was hiding behind webs of lies. here is keith morrison with the waiting car. >> our minds have a curious way of deceiving us. we cents something is off or wrong or even terrible. and yet, something in the brain wants to believe the worst did not happen. kennedy knows that feeling well . >> i was pushing away from mike gut instinct. i am not sure why. i never imagined this ever happening to one of my friends. >> i wouldn't think you would want to imagined. >> or anyone you know. my mind did not go there. >> she told herself it would be fine as she reached out from her home in salt lake city. messages to her friend mackenzie lueck. >> i saw she was opening my snap chats. i texted her and did not get a text back. this is stupid but i was wondering if she was mad at me for something. >> the mind wants a simple explanation. she knew her best friend was grieving. her grandmother had recently passed away. >> i know she was heartbroken over that. they are all very close. >> she was at the funeral. >> she left utah and went to the funeral. i thought maybe she took a few days of social media. >> mackenzie's parents had not heard from her either. after three days of escalating fear, her dad made that most dreadful phone call to the salt lake city's police department. >> yeah, i'd like to get, if possible, have a wellness check done on my daughter. i've been trying to get a hold of her and her phone goes to voicemail. i was wondering if somebody could go by her house and check on her? >> the story her dad told was this. on the night of sunday, june 16, 2019, mackenzie boarded a flight from los angeles back to utah, arriving in salt lake city around 1:35 a.m. monday. at 2:01 a.m. she texted her mom to say she landed safely. after that, three days of silence. two patrol officers went to her townhouse. her car was in the driveway. that was a good sign. repeated knocks at the door however went unanswered. peering through a window, the officer saw nothing. not a soul around. they called mackenzie's dad to report the news. next, the officers found mackenzie's friends, boss, and professors . none of them had seen her. all reasons why by the end of this unsettling day mackenzie's case was referred to a place that sounded serious indeed. the salt lake city police department's homicide squad. >> get a lot of missing person cases in salt lake city. >> lieutenant mitchell was the chief detective. >> i tried to sit through those to find the ones that raise the hair on the back of your neck for lack of a better term and this raised the hair on the back of my neck. i decided we need to take action now and at least start an initial investigation. >> truth be told, most reports are easily resolved. missing person may have lost their phone are decided to take a break from some family drama. that did not appear to be the case with mackenzie. the relationship she had with her mom and dad would be the envy of most parents. >> they were always contacting each other. they would send silly text back and forth. >> the detectives led the missing persons investigation even though their specialty was murder. >> a usual homicide investigation, there's a dead body. we're starting was something. we are moving backwards and in this case we started with nothing. >> they pulled the airport surveillance camera footage on the night of mackenzie's disappearance. sure enough, there she was. >> it was not out of the ordinary. we saw her come out of the terminal and we followed her to baggage claim she picked up her luggage. >> seemed perfectly normal. casual. >> nothing out of the ordinary that we could see. >> the last clip shows mackenzie like so many passengers getting into a car outside of baggage claim. the identity of the driver? a mystery. news of the police investigation quickly spread among mackenzie's friends. >> the second i heard about that, my stomach dropped. >> kennedy launched her own investigation. >> i went on facebook. i dropped pictures of us and i said she is missing. if you know anything, reach out to me or police. >> i thought she was still in california until i saw kennedy's message. >> ashley, another one of mackenzie's college friends put a perrone post. >> i take to rent it and because i take her facebook, some of her other family members reached out to me. >> what family members? >> a distant cousin. one who lives in utah. i said, you know, i have a feeling that she took a lyft share and i feel strongly that she did that. >> you are worried something happened in that car. >> definitely. >> ashley and the cousin called lyft and uber to see if someone it picked up mackenzie at the airport. >> that's when this began because they let it slip, lyft did, that she got in a lyft that night. >> what did you do? >> we contacted law enforcement about the lyft. >> a big break. because it gave them probable cause to serve lyft with a search warrant. >> find out where she was dropped off, what time she was picked up. >> where did she go? >> we got the destination from the airport to a north salt lake address and she was dropped off at hatch park just before 3:00 a.m.. >> a park at 3:00 a.m.? why would mackenzie come here? just as important, why would a driver leave a young woman alone, burden with luggage at a park in the middle of the night? who would do such a thing? it was the detective's job to track down the driver. who she discovered was not so easy to find. >> is this guy dodging us? >> coming up. mackenzie's friends have a terrorizing -- terrifying theory. >> abducted her. >> here is one reason why. >> her last text message we recovered was at 2:58 prior to her arriving at the location. that was the last activity ever we had on her phone. one. and keeping it off? same. discover the power of wegovy®. ♪ ♪ with wegovy®, i lost 35 pounds. and some lost over 46 pounds. ♪ ♪ and i'm keeping the weight off. wegovy® helps you lose weight and keep it off. i'm reducing my risk. wegovy® is the only fda-approved weight-management medicine that's proven to reduce risk of major cardiovascular events in adults with known heart disease and with either obesity or overweight. wegovy® shouldn't be used with semaglutide or glp-1 medicines. don't take wegovy® if you or your family had medullary thyroid cancer, multiple endocrine neoplasia syndrome type 2, or if allergic to it. stop wegovy® and get medical help right away if you get a lump or swelling in your neck, severe stomach pain, or an allergic reaction. serious side effects may happen, including pancreatitis and gallbladder problems. wegovy® may cause low blood sugar in people with diabetes, especially if you take medicines to treat diabetes. tell your provider about vision problems or changes, or if you feel your heart racing while at rest. depression or thoughts of suicide may occur. call your provider right away if you have any mental changes. common side effects like nausea, vomiting, and diarrhea may lead to dehydration, which may cause kidney problems. with wegovy®, i'm losing weight, i'm keeping it off. and i'm lowering my cv risk. that's the power of we. ♪ ♪ check your cost and coverage before talking to your health care professional about wegovy®. ♪ you're the one that i want ♪ nexgard® combo is the only monthly topical that protects against fleas, ticks, tapeworms, and more. use with caution in cats with a history of seizures or neurologic disorders. nexgard combo,... ♪ you're the one that i want ♪ ...the monthly one-and-done you want. introducing new advil targeted relief. the only topical pain reliever with 4 powerful pain-fighting ingredients that start working on contact to target tough pain at the source. for up to 8 hours of powerful relief. new advil targeted relief. 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mackenzie's phoned the detectives learned was turned off just as her right came to an end. >> her last text message we recovered was at 2:58 prior to her arriving at the hatch park location. that was the last activity ever we had on her phone. >> on the morning of june 22, six days after mackenzie went missing, the detective finally tracked down mackenzie's lyft driver. >> he said there was not a lot of conversation. he did recall her being on her phone but did not know who she was talking to. >> was a fully cooperative? >> oh, yes. he didn't seem like he had anything to do with this at all. >> because he had an alibi, a very good one actually, as soon as he dropped mackenzie off, surveillance footage captured him leaving to pick up another ride. the date and time and location confirmed by the tracking software on his lyft app . >> he continued that through the night. >> so you could eliminate him pretty easily based on the fact he was elsewhere. >> she was smiling. she was in good spirits. >> mackenzie's lyft driver told police and later us that he remembered the weird drop off location. even mackenzie commented on that, he said. >> saying how it was odd to be dropped off in the middle of the night at a park. >> he said he wasn't too worried because someone with a car was there waiting for mackenzie. >> i unloaded her luggage and said good-bye and drove away. >> who was this someone in the waiting car? the detectives were hoping they could identify him or her through mackenzie's phone records. and, she had been texting and number with a 206 area code right up to the point her phone went dead. >> we were able to take that number and run it through our database and it came back as absolutely nothing. didn't come back to anybody. >> had to be a burner phone.'s whoever that was didn't want anyone to know in official capacity. >> it was obvious at that point. >> according to the lyft driver, whoever met mackenzie at the park made no effort to conceal their identity from her. to the contrary. >> he seemed to know each other pretty well. i think all i heard was how are you doing? how was your trip? basic greetings. it seemed very safe. she knew the person that she was getting in the car with. >> did mackenzie caught a ride with someone she knew was good and bad news. the good news is it but maybe mackenzie went off with a friend somewhere. the bad news? because there was no proof of a crime, detectives lost the ability to get additional search warrants. >> we lost our probable cause that a crime had been committed. just like that. >> because of what the lyft driver said, you can't get warrants? >> correct. that was hard and it slowed the investigation at that point because we didn't have a crime to attach to it. it was still a missing person investigation. >> the detectives were blocked from getting detailed phone records which, theoretically, would have shown who mackenzie was texting. who was this friend mackenzie met at the park ? where did they go? >> investigators are about to uncover fresh clues that deepen the mystery, but also give mackenzie's loved ones a glimmer of hope. coming up. one place mackenzie was not missing was on social media. >> different people saying, i'm looking at her site and it showing she's actively online. >> her bank account was active too. too. norman, bad news... i never graduated from med school. what? -but the good news is... xfinity mobile just got even better! now, you can automatically connect to wifi speeds up to a gig on the go. plus, buy one unlimited line and get one free for a year. i gotta get this deal... i know... faster wifi and savings? ...i don't want to miss that. that's amazing doc. mobile savings are calling. visit xfinitymobile.com to learn more. doc? keith morrison (voiceover): so many questions. why did mackenzie go to a park eight miles from home so many questions. why did mackenzie go to a park eight miles from home at 3:00 a.m. no less? who did she meet? it made no sense that her friend ashley. >> i can't believe she would meet cement at the park at 3:00 a.m. it is so unlike her? >> it is? because mackenzie like most of her sorority sister talked a lot about safety. >> i have been out with her a lot of times. she has always been extremely safe. she has texted me after going out at night and say, did you make it home? are you okay? >> you would exchange things to keep each other safe? >> yes. >> ashley met mckenzie almost four years earlier. >> she was shyer than you would think she would be. she would make anyone laugh. >> kennedy met mckenzie and college. >> her family doesn't live here . she had a job. she was going to school. she was checking off everything that a responsible adult would have on their checklist, i guess. >> mckenzie grew up near los angeles, el segundo, and she was raised in the church of latter-day saints, but when she came to the university of utah to study kinesiology, according to ashley, she didn't exactly remained about. >> i know she was registered here. i heard she was never active and that made sense to me because i think she wanted to find her own path. >> you saw her changing in recent times? in what ways? >> i think she was trying to almost gain confidence in security intercell bench she would write yourself a note saying how she wanted to feel more confident because i think she realized she was shy and wanted to be more outgoing and meet people. she wanted to explore dating and it might not be how everyone else thinks dating should be. >> ashley is getting at, mckenzie was active on dating sites. so much so that by june 22, the sixth day after her disappearance, detectives had received several phone calls from some of the men mckenzie met online. mainly to say they had nothing to do with her disappearance. >> nowadays, that's how people meet people. while it was of significance because it gave us one more thing to look at, it was not this huge red flag either. >> was mackenzie on a lark with a guy she met online? a hookup she wanted to keep secret from her devoutly religious parents? that seemed far more likely than a kidnapping scenario. >> she could've gone camping or with a friend where they would lose cell service and it would be out of the ordinary. >> once they did checking around, the camping idea seemed less likely. standard procedure, they looked up airline flight records and discovered mackenzie had been booked on a flight out of town to las vegas. maybe she was there and meanwhile, the detectives begin to see activity on her bank account and something is. >> different people saying i'm looking at her site and its showing she's actively online. >> maybe she was fine, ignoring the fuss or zoned out entirely unaware. >> we were hopeful. when people go missing, even if it's on their own accord, they are making transactions were paying for stuff. we were hopeful there would be further transactions so we could find her. >> not far from the police station, kennedy and ashley hosted a rally to make sure everyone in salt lake city knew to be looking for mackenzie. >> this girl is missing and we are looking for her. we think she is in danger. >> but, was she? june 23, detectives learned mackenzie had a flight booked for that day, traveling from las vegas to los angeles. to attend a friend's waiting. >> she would not miss that. we contacted lapd and they had officers waiting for that flight to land. >> they waited for all the passengers to deplane. mackenzie was not among them. then, they learned this. it was not mackenzie who had been logging into her social media accounts. that had been her friends. >> they obtained her email and password and they were not doing it to ruin things. they were trying to monitor the sites as well to see if any information would come up. >> the activity on her bank account? >> lyft transaction and a automatic payroll deposit from work. >> them the detectives got a tip from this guy. he may be -- bring those blurry details into sharp focus. >> coming up. >> i got on the computer and within an hour, i found her profile. >> the world of sugar babies. >> i think it's more embraced for women to be up front about what they will need and want. >> did mackenzie know what she was getting into? nexium 24hr prevents heartburn acid for twice as long as pepcid. get all-day and all-night heartburn acid prevention with just one pill a day. choose acid prevention. choose nexium. nexgard® plus helps you protect your dog from fleas, ticks, heartworm disease, and more... all in one delicious, monthly, soft chew. use with caution in dogs with a history of seizures or neurologic disorders. nexgard® plus: the one you want for one-and-done protection. i'm richard lui. israel saying they rescued four hostages during a raid in gaza who had been kidnapped by hamas during the music festival on october 7. officials say more than 200 palestinians were killed by airstrikes nearby marking one of the bloodiest single days and eight months of war. president biden and the first lady attended a state dinner in paris hosted by the french president. he's wrapping up his trip commemorating 80 days since the day. where was mackenzie lueck? welcome back soto dateline. i am andrea canning. where was mackenzie lueck? the college student took a lyft to meet someone at the park at 3:00 a.m., but who? mackenzie was active on dating sites making police wonder for the right -- late night rendezvous was a hookup and radio silence was intentional. a tipster was about to share troubling details about his encounter with mack