>> with the bombing, the misconception is the blast destroys the evidence. the blast disperses the evidence, where it makes it harder for us to find it, but we'll find it. up next, an unexplained death had medical experts baffled. >> at the end of the autopsy, i didn't find anything slightly wrong whatsoever. >> each new clue raises more questions. >> the trail is getting warmer and warmer. >> until a microscopic clue reveals the ultimate betrayal. >> no one would ever expect anyone would do this sort of thing to another human being. fall means football at the university of florida. it's also time for thousands of students to get back to their studies. 24-year-old michelle herndon was entering her senior year.

after graduation, she hoped to do volunteer work. >> she wanted to go join the peace corps. she had a very long list of dreams and hopes to accomplish. >> to pay her way through school, michelle worked as a personal trainer. between classes and her job, michelle kept to a predictable schedule. but one day, shortly before thanksgiving, she didn't attend any of her classes or show up for work. >> this was so unlike her, not to return her calls or not to show up. and i guess their sixth sense was that something was very, very wrong. >> michelle's fiance, jason doyle, immediately drove the 400 miles from his home in miami to michelle's home in gainesville to see what was wrong. >> he finds michelle's house is -- it's locked up. all the doors are locked. all the windows are locked. the outside lights are still on,

as they would have been left on from the night before. >> her dog was inside, and the tv was on. through a crack in the blinds, jason could actually see what later turned out to be michelle's foot. >> when police arrived, they found michelle's body in her bedroom, face down. it was clear she'd been dead for some time. >> she was in a somewhat awkward position with her left arm folded up underneath her body. >> at first glance, there was no trauma to the body, no bruises, no wounds, no blood. >> we had no indication of what would have caused her death. >> the medical examiner thought the position of michelle's body face down was unusual. >> if somebody is sick and in the process of dying, most folks tend to end up either on their side or on their back. >> there were no foreign fingerprints in the apartment,

no signs of forced entry, and no valuables were missing. >> her vcr, her television set, her radio, jewelry, it was all intact. >> and there was no indication this was a suicide. >> if it's going to be a suicide, there's going to be pill bottles laying around and frequently a note. there was none of that on this case. >> there was a half-full bottle of beer next to michelle's body. only michelle's fingerprints were on the bottle. >> there was no indication that she had gotten drunk off the one beer that was lying on the bed. and there was other beer in the refrigerator. there was just nothing to indicate that she had passed out drunk. >> we wanted to see if perhaps something had been inside of the beer bottle, perhaps foul play,

a substance placed in the beer bottle that may have contributed to her death. >> but no foreign substances were found inside the bottle.

in most cases, the medical examiner doesn't have much difficulty determining the cause and manner of an individual's death. but michelle herndon's case was different. >> at the end of the autopsy, i really had no idea. i didn't find anything -- anything slightly wrong whatsoever. >> to find somebody that's deceased without any indication of what caused them to die, especially somebody that's that young, was highly unusual. >> the medical examiner estimated that michelle died about 24 hours before her body was found. so investigators interviewed everyone who was with michelle during that timeframe. they also checked the alibis of those closest to michelle, including her fiance. >> jason, squeaky clean. jason had an alibi of being at work and was quickly removed as a potential suspect. >> then the medical examiner

took a closer look at something on michelle's left arm. a tiny mark, smaller than most needle marks. >> we needed to find the explanation for that puncture wound. and there could be a very legitimate explanation for it. >> but michelle's personal physician said she didn't have any blood drawn before her death or receive any injections. so the medical examiner told investigators to widen their search at the crime scene, looking for possible evidence of drug use or an overdose. investigators noticed that the trash cans inside michelle's apartment were empty. on a hunch, they looked outside the apartment to see where the trash was kept for disposal. >> we went over to where the trash bins for that particular little community are stored. and on the ground, in a small plastic bag, i could see what

was visible was a bottle, a pharmaceutical bottle. and i called the investigator over and said, we got to look at this. >> the bag contained two vials of a drug labeled propofol, some syringes, and a pediatric butterfly iv. >> and it obviously had come from michelle's house 'cause contained within the bag was some mail that had been addressed to her. >> to use a pediatric butterfly iv is tiny. it would leave a tiny little pinprick that would be very hard to discover. >> the items were dusted for fingerprints, but none were found. investigators needed to know what propofol was used for. >> propofol is, in a nutshell, the world's most powerful anti-breathing drug. in the medical setting, it's used by anesthesiologists to essentially put people to sleep. >> propofol, a prescription

sedative, is an intravenous medication administered by medical professionals. too much propofol can cause death within seconds. investigators asked that michelle's toxicology tests be screened specifically for propofol. >> it's highly unusual. we wouldn't typically see propofol in our drug screen. so we've never detected it in other cases. >> as expected, tests were positive for propofol. >> i can't say with specificity how much drug she got. >> but one thing was clear, the dose was lethal. to the medical examiner, it all started to make sense. whoever it was used a pediatric-sized needle to make the tiny puncture wound in michelle's left arm, since there was virtually no hemorrhaging. the medical examiner believed that this was the work of a

medical professional, most likely someone who worked in a hospital and probably someone michelle knew. >> whoever had injected michelle herndon was someone that, for whatever the reasons were, she had trusted enough to offer that person her left arm. >> she would not have been able to administer the dose and then clean up and take that medical waste the 60 feet from her body where it was located. >> but who was this person? to find out, detective mark woodman came up with an idea that changed the course of the investigation. he told analysts to test the syringe caps found in michelle's trash. >> i can remember seeing medical staff hold needle caps in their mouth while they were giving an injection, and i thought that

there was a potential there for saliva dna. >> i thought that was rather brilliant, in fact. >> dna analysts swabbed the needle caps and found biological material. >> on the needle cap or cover, there was an unknown male dna profile. >> and scientists also found dna inside the syringe. >> i was able to determine that miss herndon's dna was present in one of them. >> proof it had been used on michelle. michelle's death was now classified as a homicide. and the murder weapon was propofol. >> i've never seen a propofol-related death. ever. >> but who wanted michelle dead?

michelle herndon's death had been ruled a homicide. the cause of death, an overdose of the prescription drug propofol. propofol is a short-acting intravenous sedative used in general anesthesia. but it's also used to treat other medical conditions. >> propofol has been suggested

as a medication to treat migraines. it's not a clear indication or definitive indication to treat migraines, but it has been reported to be helpful to treat migraines. >> detectives learned that michelle herndon had been a life-long migraine sufferer. >> from what i understand, they were bad. >> i've never had one, but people who suffer from these things tell me they're just absolutely horrible. they would go to the ends of the earth to get some relief from the pain. >> was it possible that michelle had sought pain medication from someone other than her doctor? >> they just wanted to know if michelle knew anybody in the medical field. the only person i knew was oliver. >> oliver was 30-year-old oliver o'quinn, an intensive care nurse at shands hospital on the campus of the university of florida. a background check revealed michelle and oliver were casual friends. >> i'd describe him as quirky. there was something about him, something that he felt like he had to go the extra mile to

prove himself, where most people would just be themselves. the way he acted about michelle, i kind of knew from when he first met her that he had had a crush on her. >> i think she made comments to both her friends and her mother that he was weird and that she felt sorry for him. >> then police discovered some troubling information. a review of michelle's phone records showed that o'quinn's interest in michelle bordered on harassment. >> he had called michelle herndon 43 times in less than a month, and he had called michelle herndon every single day for nine straight days preceding her murder. he never calls her again. he knows there's no one there to answer. >> o'quinn's job in the intensive care unit would have given him access to pediatric butterfly ivs like the ones found in michelle's trash. investigators wanted to see if they could link o'quinn to the

two bottles of propofol. the vials of propofol have a national drug control number and a lot number. >> those specific bottles of propofol were shipped by mckesson distributors out of lakeland, florida. >> from there, they were shipped to the shands hospital at the university of florida. >> they were shipped during the time period of when oliver o'quinn was employed there. >> specifically, they were placed in an automated dispensing machine in the hospital icu. >> i traced it to a machine that operates kind of look a soda machine. you punch in the patient number, and it drops a bottle of a pharmaceutical in your hand. >> to get the propofol from the dispensing machine, a hospital employee had to enter his employee number. and whose code was entered to get these two vials? registered nurse oliver o'quinn.

>> so i actually had that propofol all the way from the manufacturer in massachusetts to oliver o'quinn's hand in the surgical intensive care unit at the hospital. >> all investigators needed now was a sample of o'quinn's dna to compare to the dna on the needle caps found in michelle's trash. when police went to question him, they learned he had fled the country and was in ireland where he applied for a nursing license. >> he doesn't ever intend on coming back to the u.s. it's very difficult to extradite someone back from ireland. >> i had spoke with a lady who's in charge of just extradition from the republic of ireland. and i told her, look, i've got warrant in my hand. i want to arrest this man. and she said to me to the effect, no, slow down, columbo, it's going to be -- it's a very long process. >> but what was o'quinn's motive to kill michelle?

and would investigators find a way to get him back to the united states? spokesperson: the volkswagen passat is heads above the competition, but we're not in the business of naming names. the fact is, it comes standard with an engine that's been called the benchmark of its class. really, guys, i thought... it also has more rear legroom than other midsize sedans. and the volkswagen passat has a lower starting price than... much better. vo: hurry in and get 0% apr for 60 months on 2014 passat gasoline models plus a $1000 contract bonus.

investigators had two problems in the murder of michelle herndon. first, they couldn't understand

why their prime suspect, oliver o'quinn, would kill her. and second, o'quinn had fled the united states to ireland in order to avoid prosecution. to smoke him out, investigators contacted the "irish times" newspaper. >> i e-mailed them a picture of michelle, a picture of oliver, and a synopsis of the homicide investigation, and told them he was wanted in the united states. they published it on three separate occasions. >> facing increasing pressure, o'quinn left ireland and flew to the west african country of senegal, where he was immediately turned over to u.s. authorities. once in custody, investigators got a court order to obtain o'quinn's dna sample, which was then compared to the dna found on the syringe cap. it matched. >> to me, i would equate that with getting the suspect's fingerprint off the trigger of the murder weapon.

>> oliver made a great many mistakes, thank goodness. >> oliver o'quinn was charged with first-degree murder. the only remaining question was motive. >> i know he tried very hard to infuse himself into michelle's life. mostly out of pity, feeling sorry for him, she would bring him along to do things with, to go out to watch a band, to meet in the morning and have coffee. >> but in custody, oliver told a fellow inmate he grew angry with michelle because he overheard michelle refer to him as "an annoying little man." >> and we believe because of that, that sent him into this mindset that if you're never going to be mine, then you're never going to be anybody's. >> and the inmate stated that oliver confided in him that she needed a long sleep.

>> prosecutors believe o'quinn hatched a plan. he told michelle the next time she had a migraine headache, he'd be willing to come to her apartment and give her something that would get rid of the pain quickly. >> the evidence shows he got the propofol from work, typing his employee number into the medication control system designed specifically to prevent this very abuse. then he waited for michelle to call. when she did, oliver put his plan into action. on the night michelle had the migraine, oliver stopped by her apartment on his way home from work. he injected michelle with a lethal dose of propofol, using a small pediatric syringe. but he did something medical professionals often do, used his teeth to pull the plastic cap

off the syringe and left behind the dna that later identified him. michelle was dead within seconds. he positioned her arm underneath her body so the needle mark wouldn't be easily noticeable. he threw the syringes and propofol bottles into a plastic bag, which he tossed into the dumpster behind michelle's rented home, not realizing the obvious, that those serial numbers could be traced. >> i believe that the pain was such that she entrusted oliver o'quinn to administer the pain reliever, and he took advantage of that trust and intentionally took her life. >> oliver o'quinn went on trial for first-degree murder. his defense claimed he gave michelle the propofol to help relieve the pain from her migraine headache, but accidentally gave her too much. >> there's no way that the administration of propofol to michelle herndon was an accidental death.

this was an action consistent with homicide. >> the jury didn't believe it either. o'quinn was convicted of first-degree murder and sentenced to life in prison without parole. >> this is the first reported case ever involving murder by the use of propofol. so this entire case was driven by and solved by forensics. >> there is no eyewitness, so how do you put a person there without evidence? i mean, without the evidence, i don't think it would have worked. >> everybody did their job, and they did a great job, and it all came together. >> i've never had a case where the small things mattered so much, where something as small

as a needle mark or the amount of dna left on a needle cap played such a pivotal role in the resolution of a case. we gave iraq the chance. to have an inclusive democracy. >> we're going to go from mosul, to baghdad to jerusalem. and he said he was speaking in broken arabic. >> is it a crisis of enormous propositions. it is also again, it's not only a national security crisis but it's a humanitarian crisis. >> we're really close, so it's kind of like another block party except maybe a little less fun. ♪