utah, resort town, ski mecca, until he got busted on the highway for that fake passport, the new hideout for fugitive duncan martinez, a prime suspect in the murder of his good friend ron baker. park city was just the next convenient place to disappear, until that inconvenient traffic stop followed by his arrest on passport fraud charges. that changed things. so duncan came up with a new plan, -- >> we get a call from duncan martinez's attorney. informing us that duncan was willing to talk to us about what happened on the night of the murder, out of the clear blue sky. >> so, the detectives, and duncan's attorney and the da office agreed on some ground rules, he would tell the story all right, but only in exchange for some sort of limited immunity from prosecution, otherwise no story, no dice. >> we worked out a deal where he could talk to us freely, we couldn't use anything he told us against him. >> there is a term for the deal they made, they call it king for a day. fancy. >> he was in charge that day, our hands were tied as far as what could be used, but it could give us information to move forward to trying further the case. >> but, there was a catch, a big one. if duncan ever let anything slip to anyone else, or if detectives under covered any additional evidence, they could charge him with murder. but on this day, right here he had one free day pass to reveal all, no charge. so what happened that night of the summer solstice 18 months earlier, he explained that he and nathan had lured him to the spooky railroad tunnel to drink beer, meat girls, then as he walked down the tracks, said duncan, nathan tripped. ron made a joke, nathan got mad, and started stabbing him. >> ron was screaming, help me, duncan, and what did i do to deserve this? >> but, it got worse. duncan described graphically ron baker's last moments. >> he is a face looked like it was on fire and i turned to make sure that it was over and -- >> what did he do when -- >> that is when he cut his throw. >> slit his throat. and ron baker, the sweet, gentle astrophysics student was dead. then, said dunklin, he and nathan fled the crime scene and raced to a payphone where again according to duncan nathan insisted that he duncan call ron's father to say it was a kidnapping and demand ransom. duncan said he made the call worried nathan might kill him if he didn't. >> he said no you have to do this, and since you -- just looked at me -- >> then he said they went home, dumped the murder weapon, cleaned up, and went to a party in their apartment building before making a second ransom called the next morning. in short, said duncan, it was pretty all nathan's doing -- >> it mitigated a lot of his involvement in this, it minimized everything he did, at least for the most part with the i didn't think it was ever going to happen. why would you go to the extent to lure him up there if you didn't think it was going to happen? >> good question. duncan had an answer. which meant he lost his temper and snapped, excuse in a whole more dubious night. because, duncan freely admitted, they had discussed doing something beforehand. inspired by the tv show -- >> we were watching a cop show or something, and a kidnapping, and he said yeah, we should do that and definitely in a joking manner. >> or maybe, not a joke. because on the night of the summer solstice duncan admitted he and nathan took their roommate to the -- and there, for reasons he could not or wouldn't explain they killed their friend but here along after the fact he was talking like some spin doctor. >> there is no way in my mind it was possible for nathan to commit that and -- and saw no realization it could -- >> did you hear the blame shifting? not the first time detective jackson had encountered that sort of behavior from people, and in this case he was unconvinced. >> i think it was a joint thing, they were both involved there is the french term folie a deux, which translated means the minister of two. it is a psychological term that two people together get to the point where they do something that normally neither one would do on their own, it is like a one up chip on the next. >> two people acting together? they produce a breweries in this mix? >> yeah. but dunkin', the king for a day, deflected and denied always blaming nathan for killing ron. the detective garcia even tried one more time to maybe illicit some kind of confession -- >> youngkin did you -- >> know i didn't. i did not stab ron in any way. >> you know we can't use this against you? >> i know. >> in fact, everything duncan said that day was off limits, but, as we say, there was some fine print. >> we told him, you cannot talk to other people, because if you talk to other people, those are potential witnesses against you. that was part of the deal. >> sure, said duncan martinez, a deal is a deal. they had no choice but to let him go. but soon, detectives and duncan would connect once more, in ways they couldn't possibly have imagined. coming up. >> we told him, you will help us prove that what you are telling us is the truth. >> investigators or far from done with duncan martinez. >> dude, what are you doing, man? >> he was about to go undercover. >> to him, this is hollywood stuff. >> could he? when "dateline" continues. she's been looking for. sotyktu is the first-of-its-kind, once-daily pill for moderate-to-severe plaque psoriasis... for the chance at clear or almost clear skin. it's like the feeling of finding that outfit psoriasis tried to hide from you. or finding your swimsuit is ready for primetime. dad! once-daily sotyktu is proven to get more people clearer skin than the leading pill. don't take if you're allergic to sotyktu; serious reactions can occur. sotyktu can lower your ability to fight infections including tb. serious infections, cancers including lymphoma, muscle problems, and changes in certain labs have occurred. tell your doctor if you have an infection, liver or kidney problems, high triglycerides, or had a vaccine or plan to. sotyktu is a tyk2 inhibitor. tyk2 is part of the jak family. it's not known if sotyktu has the same risks as jak inhibitors. find what plaque psoriasis has been hiding. ask your dermatologist about sotyktu for clearer skin. so clearly you. sotyktu. after advil. feeling better? on top of the worlddddd!!! before advil. advil targets pain at the source of inflammation. when pain comes for you, come back fast with advil liqui-gels. can we get real clear about life with psoriasis? yeah, i'm ready. is your treatment leaving you with uncontrolled symptoms? like the cover-it-ups and brush-it-offs? enough with good enoughs. don't stay hiding or hurting. when your lotions and creams don't do enough to help treat the inflammation beneath the skin, causing plaques and pain, it's time to get real about psoriasis, so, your dermatologist can help you get clear. make the appointment and ask about real clear skin. travel. there is nothing like it dancing is my passion. but with my moderate-to-severe eczema, it hasn't always been easy. i was constantly itching. whatever i was doing now, i'm staying ahead of my eczema there's a power inside all of us to live our passion. and dupixent works on the inside, to help heal your skin from within. it helps block a key source of inflammation inside the body that can cause eczema. so, adults can have long lasting, clearer skin and fast itch relief serious allergic reactions can occur, that can be severe. tell your doctor about new or worsening eye problems, such as eye pain or vision changes, including blurred vision, joint aches and pains, or a parasitic infection. don't change or stop asthma medicines without talking to your doctor. healing from within is a powerful thing. ask your eczema specialist how dupixent can help heal your skin from within. after advil. feeling better? on top of the worlddddd!!! before advil. advil targets pain at the source of inflammation. when pain comes for you, come back fast with advil liqui-gels. >> day after day, the trains day after day, whethe trains rolledyou, roll through the dark manson tunnel, parsed these strange graffiti, past the place where ron baker breathed his last. two years went by. duncan martinez returned to the good life in park city, utah, while detectives turn their attention to his old pal nathan. he was not hard to find -- >> nathan, we learned, was arrested for a bank robbery he pulled with somebody he was doing drugs with. >> so now, nathan was locked up in the county jail in riverside california, totally unaware has but he had betrayed him. though duncan story about what happened in that train tunnel wasn't a betrayal, but was it true. you can't charge a man with murder based on blame from an old accomplice. mind you, there was some forensic evidence, a little, traces of blood under ron's fingernails, where blood type a b. duncan was taipei. but what about nathan? >> we got a search warrant for his blood, and that came back ab positive. 4% of the population had it. >> that was good, quite good, but still not enough for a murder charge. detectives needed to place nathan inside the tunnel with the knife in his hands. one possibility, would the guy who had ratted on him help him some more? >> we had established a relationship with duncan, he knew where we were coming from, we wanted to get ron baker's killer, he told us, and we told him, you will help us, and what you are -- eager to help throw nathan under the bus, the recorded phone call was set up through the jail, and nathan and duncan spoke for the first time in almost two years. >> what are you doing? >> everywhere, i ended up in boston for a while. you have been in a lot of trouble. >> it was like old times, as they too caught up, then duncan started spinning his story, to get nathan talking. >> i just got in touch with my mom, and she says they have been over at her house giving serious -- about my blood type and stuff. >> then, without missing a beat, duncan cleverly got nathan inside the tunnel, and tied into the struggle just before ron baker was stabbed to death. >> remember, you got your hand scratched? >> we wrestled and stuff. and -- i don't know if it is -- >> nathan got nervous. but before they wrapped up the call, an unexpected bonus. an ex -- duncan had just duped him, and he invited his old friend to visit him in jail. and four days later, there he was, wearing a wire. >> you have to understand his personality, to him this is hollywood stuff here. i could really pull this off. >> -- screaming my name to help him out, dude i thought i was going to die. >> then, duncan went to work, to try and draw nathan out by claiming he had left behind his blood on the walls of the tunnel. >> on the wall. >> -- >> he played it, downplayed it down. >> -- >> that was good, but detectives in the da's office still wanted a little bit more evidence before indicting him for murder, and duncan, thanks in part to his limited immunity agreement, he remained free as if he had never harmed a hair on his head. him and the baker family was not happy, not at all. >> i did not like it, my parents did not like it, dunkin'walking away, i mean he was friends with ron for a long time. he had been at the, house talked about him at the funeral, at any point he could have said what happened. >> but duncan did not seem to care. he was about to embark on a whole new chapter of his life. at the university of utah, a man who liked to tell stories, now had plans to make movies. coming up -- >> he went by the name -- >> he had a leather jacket, he had a tattoo, he had a little bit of the bad boy thing. >> a whole new role for duncan martinez, and an encore undercover performance. >> i don't know what to, do i don't know what to tell, him what should i tell him? >> yeah, and? >> that you don't know who did. >> when "dateline" continues. >> but duncan did not seem to care. he was about to embark on a whole new chapter of his life. at the university of utah, a man who liked to tell stories, now had plans to make movies. coming up -- >> he went by the name -- >> he had a leather jacket, he had a tattoo, he had a little bit of the bad boy thing. >> a whole new role for duncan martinez, and an encore undercover performance. >> i don't know what to do, and i don't know what to tell him, what should i tell him? >> yeah, and? >> that you don't know who did. >> when "dateline" continues. the power goes out and we still have wifi to do our homework. and that's a good thing? great in my book! who are you? no power? no problem. introducing storm-ready wifi. now you can stay reliably connected through power outages with unlimited cellular data and up to 4 hours of battery back-up to keep you online. only from xfinity. -- home of the xfinity 10g network. and his name was duncan martinez. >> he rushed a fraternity at the university, he was really liked by most of the fraternity members, he was living a pretty good life. >> yes he was, 22-year-old duncan martinez once a big time murder suspect was now a big man on campus. >> he went by the name doofus o'reilly, that is what he liked to tell his friends to call him. he was a center of attraction. >> charming, charismatic, life of the party, doofus, aka duncan, was a long way from that murder in the tunnel. and here he soon caught the eye of sorority sister melissa, the two started dating. >> i hung out at a particular fraternity house and he was pledging the fraternity, so we got to know each other and he was quick, witty and i liked that. he had a leather jacket, he had a tattoo, he had a bit of the bad boy thing. it was as if guy fieri had rolled into the college with the hair and look, and the big stories. >> melissa said it was like he dropped in from another planet, but he instantly fit in. >> i think people naturally followed him, i think they're very much like tim, do not conclude, identify with -- anyone that they were into. he had a lot of capacity for dazzling people. >> when you compared him to the other young men around the fraternity, aren't the college, what was he like compared to them? >> flamboyant. >> like it wasn't an about-face or something? >> he wasn't. he told the stories of another place, of something else. >> what was your tendency then? when you listen to these stories and go on, or would you -- >> i sort of thought, okay, sure, and sort of went along with it. i think everybody did. i mean, we were 21, 22. >> back in l. a., the detectives are still investigating and he run baker murder. they wanted to put duncan's dazzling, but devious skill set to use one time. and get one more blockbuster piece of evidence. they found duncan on college, and persuaded him to make it another call to his buddy, who is still behind bars. maybe this time, duncan could spark something incriminating out of nathan, to seal their case and charge it. >> we flew to utah, and from a marriott hotel they talked about a half hour, and little by little it started coming out. >> naturally, the call was recorded. >> hello, hello, talk to me. >> he did talk as usual, spinning another -- for his arrest, and he feared taking the rap for ron's murder. >> all i know is that when we left, i don't know what to do. i don't know what i will tell him if i go down. what should i tell him? >> yeah, and. >> that he did nothing. >> he kept trying to get anything to say the, words to take the blame directly for stabbing ron. for cutting his throat. >> this is some -- that is why i wanted to talk to you about it. >> you -- how can you ask for forgiveness for something. >> i don't understand. so that makes it better? >> it doesn't make a. better doesn't make it worse. it makes it -- do what i have to do. >> then, duncan played, it sounds like you have it tucked away like it never happened, and i can see how you could do that. >> i have to live my, life i have to go on. >> it happened, it was a mistake. not quite a confession, but close enough. now, two years after's murder, nathan was -- but duncan martinez, he would resume college life, film studies, frat parties, and freedom. after he wrapped up this undercover call with nathan, detectives drove him back to campus, and dropped him off. >> as he was getting out of the car, it is really too bad that we had to meet under the circumstances, because i thought you would be a lot of fun to hang out with you guys. >> was duncan martinez literally getting away with murder? maybe. he was too smart to screw that up. wasn't he? coming up. >> he told me he had witnessed a murder. >> duncan's secret. >> i remember thinking this has to be something he made up, surely this would be something that would have caught up with him. >> was it about two? >> it is almost as if he knew his facade might have been slipping. >> when "dateline" continues. >> he told me he had witnessed a murder. >> duncan's secret. >> i remember thinking this has to be something he made up, surely this would be something that would have caught up with him. >> was it about two? >> it is almost as if he knew his facade might have been slipping. >> when "dateline" continues. rsv can severely affect the lungs and lower airways. but i'm protected with arexvy. arexvy is a vaccine used to prevent lower respiratory disease from rsv in people 60 years and older. rsv can be serious for those over 60, including those with asthma, diabetes, copd, and certain other conditions. but i'm protected. arexvy is proven to be over 82% effective in preventing lower respiratory disease from rsv and over 94% effective in those with these health conditions. (♪♪) arexvy does not protect everyone and is not for those with severe allergic reactions to its ingredients. those with weakened immune systems may have a lower response to the vaccine. the most common side effects are injection site pain, fatigue, muscle pain, headache, and joint pain. i chose arexvy. rsv? make it arexvy. (♪♪) you deserve better than that. i'm hungry, i'm in a hurry, i don't have time to make anything healthy. you could if you had a blendjet. blendjet? it's the portable blender that makes the healthy choice the most convenient choice. i don't know. it seems like a hassle. hahaha! wrong. just pour in some milk, add some frozen fruit, and bam! you've got a nutritious and delicious smoothie. mmm! that is good. you're welcome, sad office guy. get yours today at blendjet.com are we in in an ad? we sure are. >> i'm richard louis with the hours tough stories. second child has died in the nursery at the hospital in gaza city. according to a spokesperson. the palestinian ministry of health. he says the generator stopped working in the icu and pediatric units. the hospital is now considered out of service due to heavy bombardment. president biden marked veteran days in a cemetery, he spoke after a ceremony and said america's veterans are quote the steel spine of the station. now, back to dateline. back to dateline. >> he was the charismatic guy if duncan martinez was the charismatic pied piper of his university, melissa was, well let her describe it. >> i was president of my sorority i was going to be chief justice of the judiciary, i was exceptionally capable and kind of nerdy and boring, i drove all vote was basically of all for who i was the phone call search. the unconcealed to love impressing melissa, is that what he told her a story that was more disturbing than impressive. >> he told me he had witnessed a murder -- >> he's walking up to the edge of something -- >> he never got into details but told me he was helping the police with it. >> dunkin'fun loving film student and party animal. doofus o'reilly tangled up in murder? but for once duncan seem serious, that lee serious. >> he said that he and a roommate had talked about going after a college friend, and that there had been an intentional plan. >> that he was a part of. >> that it appeared he had been a part of. yes. i remember thinking it was some