for something that we didn't do. and -- i just -- and i don't understand why they did it. during a church service, he died later that night of a heart attack. one year later, steve's daughter studied the lines of "claudius the king." >> my words fly up, my thoughts remain below. words without thought, never to heaven go. >> in these words, a clue to her father's death.

the cities of dallas and ft. worth, texas. locals call it the metroplex. it's the largest consolidated metropolitan area in the state, known for the assassination of president kennedy in 1963. 38-year-old steve robards was a texas native and worked as a mail carrier. >> very proud of his job. he was a rural postman, but he liked his job, he liked being outdoors and felt some pride in it. >> his 16-year-old daughter, marie, had recently moved in with him after a disagreement she had had with her mother's husband. >> they were live in an apartment and he was on the list

to get the next larger apartment. he was happy having his daughter and wife at this point. >> marie enrolled in eastern hills high school where she was a popular student. >> quiet, studious, elegant. the kind of girl that you looked at twice and wanted to get to know because she seemed so reserved. >> by all accounts, both enjoyed living together. but their lived changed forever on the night of february 17th, 1993. just after dinner, steve attended an evening church service. when he returned home, he told his girlfriend and daughter he wasn't feeling well. >> he started getting severe stomach cramps and they became more severe as the night progressed. after a few hours, 911 was

called and he went into what appeared to be a coma-like state right there in the living room. >> he began to foam at the mouth and by the time the ambulance guys got there, he was dead. >> an autopsy revealed the death was caused by cardiac arrest. >> i didn't want to believe it. how could it be that bad. he was 38. how could it be that serious? >> his heart was mildly enlaunchenlarged and i signed it out as a natural death. >> after his death, marie went to live with her grand parents. >> from one year, marie lived the kind of perfect life every parent would hope their child would live. she never got in trouble, always

turned in her homework. she dated some but she was never in any way regarded as a wild girl. >> after >> after graduation, marie used the $60,000 she received from her father's life insurance policy to attend the university of texas. she majored in premed. her dream was to become a pathologist. midway through her freshman year, marie learned that police were investigating her father's death. they questioned how a 38-year-old man could have died of a heart attack so young. >> it was, by all accounts, the perfect crime. coughing disrupts everyone's life. that's why so many people are turning to delsym for longer lasting cough relief. delsym has an advanced time release formula that helps silence coughs for a full 12 hours. up to twice as long

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after steve robards' unexpected death, his daughter, marie, transferred to a new high school and made a new friend, stacey high. >> i would have to say we were best friends, you know. we kind of fell in love with each other, you know. just, it was -- we had so much in common. >> stacey sees in marie -- she sees something in marie. she sees through her in a way.

she realizes that that poise and perfection is disguising something. >> during senior year, stacey and marie were both required to read shakespeare's "hamlet" for english class. as they read the play together, stacy happened to begin with claudius's soliloquy in act three in which claudius agonizes over his decision to repent for killing hamlet's father. >> my fault is passed, but oh, what form of prayer -- >> forgive me. that cannot be. i'm still possessed for those effects for which i did the murder. >> so stacey reads the line and goes, isn't that cool, marie, how that's written? and marie is standing, frozen, and tears begin to stream down her face. >> she asked me, stacey, do you think people can go through life without a conscious? >> there was stacey with her questions.

you have a secret? yes. you've done something? yes. and, you know, stacey's first question, oh, my god, you're pregnant. marie went, no, it's worse. >> so after a while of guessing, i said, did you kill someone? she nodded her head yes. >> and that's when marie broke down and cried. >> i can't talk about this right now. >> marie then admitted the unthinkable, that she murdered her own father. she said she did it with a poison she stole from her chemistry class a year earlier. >> be very careful with this stuff. >> marie said that she took the poison when the teacher's back was turned, placed it in a paper towel, and hid it in her backpack. one week later, while preparing dinner, marie mixed it into her

father's mexican food which concealed the taste of the poison. the poison she used mimicked the signs of a heart attack, and her father died a few hours later. the autopsy never detected the poison in his system. after the confession, marie swore stacey to secrecy. if the pledge was broken, stacey knew her best friend would spend the rest of her life in prison. >> stacey is tormented, however, by this secret she, too, is trying to keep. and she begins to have these nightmares. >> in one of these recurring nightmares, stacey hears the voice of marie's father calling from the grave.

in another, stacey sees marie chasing her endlessly through the night. >> she begins to lose her ability to focus. she can't concentrate in school. her grades go down. she begins to drink too much at high school parties. at one point, she asked her mother if she could check into a psychiatric hospital for adolescences. and no one can figure out what had happened to stacey. it seemed like the classic meltdown. >> stacey knew if she said anything, it would be her word against marie's since steve robards' death was ruled to be from natural causes. however, the pressure on stacey high was too great. she told her mother, the school guidance counselor, and eventually the police. >> she finally had to confess, but marie never would.

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when stacey high told police that steve robards had been poisoned, the police searched the chemistry lab where his

daughter, marie, said she stole the poison that killed him. in the lab's safety manual, the page describing the chemical marie allegedly used had been torn out. >> it also tells you what precautions you need to take when using the substance. it also tells you what to do in case it is swallowed or your eyes come in contact with it. >> if marie used the poison to kill her father, why hadn't it shown up during the autopsy? >> it's not a normal procedure, unless there's some indication that we need to do that. it's testing that we don't do here at the facility and we have to send out for, and the investigation did not lead us to suspect anything of that nature at the time of the death. >> the chemical she used, the only way it could be detected, is if the medical examiner in ft. worth had a machine that cost $150,000 that could detect the trace of this chemical during an autopsy, which they

didn't have and which they never even thought of using. >> the technology, which can find rare chemicals in human tissue is called a mass spectrometer gas chromatograph. since marie planned to attend medical school and become a pathologist, prosecutors suspected she was familiar with the screening test used by the local medical examiner. she also knew which poison wouldn't be detected. investigators hoped that steve robards' tissue samples were still in storage since his death 18 months earlier. >> the medical examiner's office was within days of destroying the tissue samples and the blood samples, as they do when there's nothing amiss, they don't suspect foul play or homicide. >> the tissue samples were sent to an independent forensic laboratory in pennsylvania,

where they were analyzed with the mass spectrometer gas chromatograph. the poison they were looking for was a metallic substance and very rare. we will not reveal the name of the poison on this program. the gas chromatograph mass spectrometer directs a beam of electrons on the sample, breaking its molecules apart for analysis. the results are charted on a graph. each peak is a separate compound. the size of the peak is proportional to the amount present. the number is the exact time in minutes it took for the compound to travel through the column from the moment of its injection to detection. in steve robards' sample, scientists found a metallic compound with a retention time identical to the poison his

daughter marine admitted stealing in the chemistry lab. and the amount found in steve robards' body was massive. 28 times the lethal dose. with this news, ft. worth homicide detective thomas bocher went to the university of texas in austin to see marie robards. >> she came out in the hallway and i introduced myself. i told her she was under arrest for the death of her father, steven robards, years earlier. she had no response. there was no reaction. >> and marie quietly went with them, poised as ever. and once they got in that little room, they barely had to ask a question and she confessed and broke down. >> and she was pretty forthcoming with information fairly quickly. she didn't try to hide. she apparently was either guilt-ridden or had thought a lot about what she had done and came forward with the information. >> the most fascinating aspect

for both the police and for journalists covering the case was marie's explanation of her motive. >> what was it that made you want to kill your father? and she said, i wanted to be with my mom. >> but in an ironic twist, like something out of a shakespearean tragedy, it was all in vain because marie robards's mother and her new husband were planning to move to florida and didn't tell her until after her father's funeral. marie had no choice but to move in with her grandparents so she could finish high school in texas. >> and thus began this tale that, in many ways, is a kind of twisted modern parable of teenage girls in the suburbs. these girls that have those

mercurial emotions, but also many of whom are girls of divorce who are trying to grow up with parents who have split up and seem often preoccupied with rebuilding their own lives and forget about the needs of their own children. >> despite her confession, marie robards surprised everyone by deciding to plead not guilty. she now said she hadn't planned to kill her father at all. at ancestry, we call it a hint.. our little leaf that helps guide you through the past. simply type in a name and you're taken on a journey. a journey that crosses generations. and continents. all to tell the most amazing story. yours. discover your story. start searching for free now at ancestry.com

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in 1996, marie robards went on trial for the murder of her father, steve. she pleaded not guilty. her defense was that she had no intention of killing him. marie admitted that she stole the poison from her high school chemistry lab. and she also admitted that she put the poison in her father's mexican food, but she said she only planned to make him sick, not to kill him. >> of course that doesn't make that much sense. if he just got sick, she wouldn't get to go back with her mother. >> prosecutors said marie was a straight "a" chemistry student, and the amount of poison used was 28 times the lethal dose.

>> anybody who is going to go to a local medical school to study is probably -- if they're a high school student -- is probably above average as far as in the science department. and as a matter of fact, i mean, that was part of my investigation. i collected her grades, and she had very high marks in school and in the sciences. >> are you feeling any better? >> i feel lousy. could you get me some ginger ale? >> sure. >> they also pointed out that marie stood by and watched her father die, without saying a word to her father's girlfriend or the ambulance crew that tried to resuscitate him. 18 months later, the gas chromatography found what the first autopsy did not, that steve robards had died of a massive dose of poison. the prosecution presented marie robards' signed confession as

evidence. >> did you know that this stuff is dangerous? yes or no? >> yes, sir. >> how did you know that? >> because my chemistry teacher said it. >> said what? >> that it was dangerous. >> stacey testified that marie told her that she always knew that enough of that chemical would have killed her father. and that was the defining moment, that her best friend admitted that marie had the knowledge about what that poison would do. >> the forensic evidence, the confession, and the testimony of her own best friend all worked against her. >> the prosecutor in the case called her a relentless predator. another prosecutor called her society's worst nightmare, a girl who kills her dad.

but some people saw her as a kind of lizzie borden of texas. this sweet, charming, successful, industrious, young girl who suddenly did something inexplicable. and in this surprising twist, at least for me, i began to sense a sympathy developing for her, because in many ways, she was the symbol of what modern divorce has done to our society. >> on may 9th, 1996, it took the jury less than an hour to find marie robards guilty of murder. she was sentenced to 27 years in prison. >> i don't know what we do about it, but they are kids. they don't think exactly like adults. that doesn't mean they can get by with something like this with a slap on the wrist, but 27

years seems a little excessive to me. >> what she had done was commit the perfect crime. it was, by all accounts, the perfect crime. >> had dorothy marie not mentioned it to a friend, she probably would have gotten away with it, almost certainly would have gotten away with it. >> marie has never spoken about what's happened since. what is known is that marie is the model prisoner at this women's prison in texas where she's going to be staying the next several years. she has never complained. that she always volunteers for the worst chores, that one day a psychologist went to see her and she was wearing this paper thin prison garb, and a cold front had come through texas and she was shivering. the psychologist said, why don't you ask for something warmer? she said, i don't deserve to. she shrugged, she smiled, and she said, i'll be okay.

in 1996, a fire broke out in a rental home in north carolina. one child died, another was critically injured. to the family, the fire was a mystery. to investigators, it was murder. >> tabor city, north carolina, a small rural sweet potato farming community in the western part of