it doesn't matter what they say. there's too many con artists today. a brilliant, young architect mysteriously died just before she testified in a criminal trial. her diary contained stories of sex, betrayal and intrigue. investigators needed to know if the stories were true. university park, texas, just outside of dallas, is better known as the bubble. it's a place of privilege and prestige, an address many would like to have but few can afford. >> it's kind of the beverly hills of dallas. that's the way the park cities is.

>> nancy dillard lyon lived most of her life in texas. she was a harvard-trained architect and the daughter of a wealthy and well-connected dallas family. nancy met her husband, richard, while at harvard. they married and soon had two children. >> they had great energy, great friendliness. when we moved in, they gave gifts of ice cream and they baked cookies and bring them over to us. and my husband, who i've said is rarely hyperbolic about anything, used to say she was the nicest person in the world. >> nancy became the youngest partner in the history of a trammell crow, a large real estate development firm. but success came at a price. >> i think she always had, as many women did at that time, a conflict between the amount of hours that she wanted to work to develop her career and time spending with her children. >> nancy was also experiencing some physical ailments.

and on a january night in 1991, her symptoms included vomiting and severe stomach pain. her husband, richard, took her to the hospital emergency room. doctors were initially baffled. >> she was seen by multiple consultants, infectious disease, gastro neurologist, pulmonologist, nephrologists, and because of her multi organ failure. and still, in spite of all the resuscitation measures, she was not recovering. >> nancy's condition deteriorated, but she provided doctors with a potential clue. she said she first got sick several months earlier after drinking some wine from a bottle left on her doorstep. >> she thought it was a gift from a neighbor, that it was just a, you know, a house-warming gift, so to speak, from a neighbor.

>> and she drank that wine and became violently ill later that day. she had nausea, vomiting and abdominal pain. >> but that had been months earlier and didn't explain her illness now. >> even though i had suspected something foul play, but really can't -- you couldn't pinpoint anything. >> doctors sent nancy's urine samples for testing, but her condition began to deteriorate, her organs failed, and she was put on life support. >> it was clear that she was not going to recover. nobody could really understand it. >> six days later, nancy dillard lyon was dead. but doctors were suspicious, and they weren't the only ones. >> i was married to a nurse. she had taken care of nancy dillard in the trauma center. she said she looked like she had been poisoned to me.

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when the daughter of a wealthy dallas family, nancy dillard lyon, died under mysterious circumstances, her doctors made two telephone calls. one was to the medical examiner to suggest a thorough autopsy.

>> and i told him, listen, i have a patient here. i suspect foul play. >> the other was to police. >> they thought the death was suspicious and needed to be investigated. and it was suspicious and it was investigated. >> investigators learned that nancy was about to testify at the embezzlement trial of her former boss from trammell crow. nancy told friends she was uncomfortable at the thought of testifying against her former colleague. part of that may have resulted from a threatening letter she received. >> stay out of the bagwell case or you and your family will face the wrath of god. >> it's, i guess kind of a veiled threat. no one ever knew where it came from.

>> at nancy's autopsy the pathologist found no signs of disease in her internal organs. but toxicology tests revealed some surprising results. nancy lyon had been poisoned with arsenic. >> all the specimens showed significant amounts and levels of arsenic. and what that shows is that the poison was absorbed through the gi tract, that it was distributed through the blood. >> patients often don't know they're poisoned since the symptoms are so common. >> people don't think about a poisoning immediately. they think it's just a natural thing. and when you have nausea and vomiting, that certainly is a common symptom. >> most of the poisonings that you see nowadays are of a much more sophisticated variety that are harder to detect initially or even after doing tests. so, arsenic was a surprise.

>> the manner of death was ruled a homicide, but questions remained. investigators discovered a receipt among nancy's papers, a receipt for arsenic. nancy's husband, richard, said she bought the poison to kill a colony of fire ants in their yard. and friends also revealed nancy had been depressed over the past year. she discovered her husband was having an affair and the couple briefly separated. >> richard had met another woman. and she felt he was going through a mid-life crisis. so, she said -- at first, her take was, hey, i'm going to stay patient. i'm going to get some counseling because she was just devastated, really. >> i wouldn't discount a woman making herself ill or even taking something to make herself ill to get the attention of her husband. >> yet, medical experts were skeptical that nancy committed suicide.

>> i don't believe that for a minute. i mean, you've got someone who's dying a very, i would consider hideous death, certainly capable at any time of voicing that she had taken the poison because the symptoms are, you know, both painful, and you certainly are deteriorating with this. >> absolutely ludicrous. i mean, she had two children she loved dearly, she was a mother, she was young. she had everything to live for. >> also among nancy's papers was a diary, and it contained a blockbuster revelation. she accused her older brother, bill, of sexual abuse when they were younger. nancy said she feared her brother and questioned his ability to control himself. "sex, sick sex," the notation read. "with me, my girls." nancy's brother angrily denied the allegation but couldn't explain why she had written this in her diary.

her family strongly suspected richard was the killer since they knew he was having an affair with another woman. >> i did not poison my wife, nancy dillard lyon, nor did i have anything to do with her tragic death. >> so there was no shortage of suspects. who sent the wine to nancy's home? who sent the threatening letter? why did nancy accuse her brother of sexual abuse, and would he kill to keep her quiet? and was nancy planning to divorce her husband? >> in the event that this case becomes a murder charge, this will be an honest to goodness perry mason-style whodunit.

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investigators had plenty of suspects but little evidence in the poisoning death of nancy lyon. the only thing they knew was that nancy didn't kill herself. >> no way you would do it. it's too painful. it's too drawn out. it's a horrible way to die. and you're very aware and very conscious until the very end of it.

there is no way to kill yourself that way. >> when a person ingests arsenic, the poison attaches itself to the hair follicles. as the hair grows, the poison residue remains on the hair shaft and becomes a permanent record. so scientists cut nancy's hair into 7-millimeter pieces. each piece corresponded to a two-week period. each piece was placed in a separate vial and then exposed to radiation in a nuclear reactor. >> the sample can be analyzed as is in most cases, just simply weighed into a radiation vial. most other methods require dissolution of the sample. >> when scientists examine the hair with gamma ray spectrophotometry, they discovered a startling piece of

information. nancy had ingested small doses of arsenic every week starting four months before her death. the dose of arsenic increased four weeks before her death. the highest amount of arsenic was in nancy's system two weeks before her death. >> her levels were anywhere from 4 to 100 times what normal levels were, so, it was a very significant level and it was lethal. >> the forensic tests showed the poisoning started when nancy's husband, richard, moved back home after the separation. but richard wasn't the only person in nancy's life who had both motive and access. nancy's handwritten diary alleged her brother, bill, had sexually abused her as a child. investigators wanted to know whether this was a possible motive. to see if these entries were

written by nancy, investigators sent the diary to a forensic document examiner, hartford kittel. >> handwriting examination's based upon two distinct facts -- no two people write exactly alike. within the writing of a single individual, there is normal variation. it's this normal variation that we associate or we don't associate with the questioned writing. >> surprisingly, nancy and richard's handwriting looked strikingly similar. friends said this was intentional. while in college, nancy had written some of richard's research papers, and she mimicked his writing. kittel first looked at known handwriting samples from both nancy and richard. despite their similarities, there were differences.

>> she used her ampersands quite extensively through her writing, so every fifth, sixth line would have an ampersand on it, in her known handwriting, where richard always used the a-n-d for the verbiage and. >> kittel also noticed that nancy and richard made their capital "i" differently. >> richard used one down stroke like a 1, whereas nancy used a down stroke and then a cross at the top and bottom. she was willing to take a lot more time in executing them than richard was. >> their lowercase fs were different as well. >> richard used a clockwise motion coming down from the top of the "f" down to the bottom. he would swing off in a clockwise motion to finish off the lower loop of the "f," whereas nancy always came down and went counterclockwise to finish off the "f." >> kittel concluded richard wrote the diary entries about nancy's brother, bill.

>> absolutely certain that he had written that. >> 100% certain? >> yes. >> prosecutors now believed richard lyon had forged nancy's diary to cover up the murder. >> it never crossed his mind he was going to be caught. he thought he had it aced, and he certainly didn't think it would be his own handwriting.

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no one granted him the power of god to take her life. she was slowly poisoned to death. probably one of the most hideous things that you can do to someone. this wasn't done in a moment of passion or anger of picking up a weapon that was handy to him. this was done with slow premeditation and over a period of time, and it's a hideous, hideous way to murder somebody. >> richard lyon insisted he had nothing to do with the poisoning death of his wife, nancy. as proof, he offered a receipt for arsenic that he said nancy had signed. prosecutors asked forensic experts whether this was, in fact, nancy's signature. >> i wasn't able to reach a conclusion as to authorship.

>> but the owner of the company listed on the receipt told prosecutors all they needed to know. >> did you sell her these chemicals? no, i didn't. is this a receipt? do you sell chemicals? no, i don't. is this your receipt from your business? no, it's a forgery. it's not mine. >> investigators also discovered that arsenic was not shipped to the lyons' home. it was shipped to a post office box richard opened. >> there is no reason for the world to have a post office box opened for him to get this arsenic. if everything is completely legitimate, why aren't you having it delivered at home or where you work? because it's a nefarious reason of having it delivered to a post office box. >> in the hospital before she died, nancy lyon told her doctor about a suspicious incident that occurred several months earlier. >> she said, well, at one time when they were separated, they had gone to the movies together. and richard had gone and got her

adrink, and when he brought it to her and she drank some of it and she said it tasted awful, and when she looked in there, there was a white powder on the top of the drink. >> nancy said she became violently ill later that night and told her doctor something else. >> my husband, he's been giving me these capsules for the past several months, and he would say, nancy, go take these, these are like vitamins and these are good for you. >> police confiscated every pill in the lyons' home and sent them for forensic testing. two pills tested positive for barium carbonate, a toxic chemical used in the production of glass. despite her suspicions, nancy never directly accused richard of poisoning her. >> nobody wants to believe that they are married to somebody who can murder. i mean, because then what are you saying about yourself?

>> and it's kind of outside the realm of most people's reality, that someone would poison you. and i don't think she wanted to believe it, and i think that she was embarrassed or ashamed to say anything about it. >> prosecutors believe the motive was money and the desire to live with his girlfriend. >> he didn't want her. he wanted the family affiliations and alliances. i think it was partly money and it was partly just the position that he wanted, and he couldn't have either one with just a divorce. >> prosecutors believe richard first tried to kill nancy by putting barium carbonate in her vitamin pills and may have put it in nancy's soda at the movies. when that didn't work, he used arsenic. forensic testing showed nancy started ingesting arsenic in september, around the time she and richard reconciled.

the fatal dose was administered two days before nancy was admitted to the hospital where she died. to hide his involvement, richard created the fake invoice for the arsenic. and forensic analysis proved that it was richard who wrote the sex-related entries in nancy's diary implicating her brother as a possible suspect. >> i think it was calculating. he thought himself as a lady's man. i think he was a cold-blooded killer, and he did it in the most despicable way possible, slowly ingesting arsenic to his wife. >> when he went on trial for murder, richard lyon pled not guilty. but the forensic handwriting analysis, the timeline of the

poisonings captured in nancy's hair and the discovery of poison in vitamin pills found in the home were difficult to deflect. richard's girlfriend even testified, claiming richard lied by telling her that nancy had a rare and fatal blood disease. >> any time that you catch a defendant or any witness in a lie -- and that was a pretty big one -- and i don't think it's a coincidence that she was going to die from a fatal blood disease. i think that those things immediately begin to color their view of him, and he was a liar. he would lie. >> it took a jury less than three hours to convict richard lyon of first-degree murder. he was sentenced to life in prison. >> i worked lots of cases like this, and the question was always why not just a divorce. >> you know, they may be intelligent, but they're criminally stupid, and for good reason. and thank god they are, because we couldn't catch them. >> it was hard for me to believe

that he had actually killed his wife. and it had just finally broken down based on the shape of an "f" and an "l" and an "r," and just scratchings on a piece of paper. for years, criminals used women's hosiery as a mask to hide their identities. but today, to a forensic scientist, hosiery can be as valuable as a fingerprint. because of its signature characteristics. and textile science identified a killer when an eyewitness couldn't. in the small midwestern town of herron, illinois, murder was like a virtual stranger. it's so rare, that police thought this 911 call as a prank.