On the evening of January 8, 1991, Nancy Dillard Lyon fell suddenly and violently ill. The pain in her stomach was severe, and her condition only worsened as the hours passed. Her husband, Richard, called her doctor, who suspected food poisoning and recommended a specific medication. Richard went to the pharmacy, brought it home, and gave it to her, but it did nothing to help.
He then took her to the hospital, where she was admitted for further tests. The doctors ran a series of examinations, but none of them revealed the cause of the problem, even as Nancy’s condition deteriorated hour by hour. Her breathing became labored, her blood pressure dropped to dangerously low levels, and by the morning of the following day, her organs had begun to fail. By then, the doctors suspected Nancy might have been exposed to some kind of poison and ordered additional tests, but her condition was deteriorating too quickly for the cause to be identified in time.
Several of her organs stopped working, she lost the ability to breathe on her own, and she eventually fell into a coma. The doctors continued to do everything they could to save her, but it quickly became clear that there was no chance of recovery. Her family was told that they had to make the difficult decision to remove life support. Six days after she was admitted to the hospital, Nancy died.
Because the doctors had been unable to determine the cause of her death, her body was sent to the Dallas County medical examiner’s office for an autopsy. But there was another reason as well. By that stage, they were seriously considering the possibility that Nancy had been deliberately poisoned. While she was still conscious, Nancy had told one of her doctors that she believed someone might be trying to poison her.
According to Nancy, the strange incidents had begun about four months earlier, when she found an expensive bottle of wine with an unsigned card on her front porch. Assuming it was a gift from the neighbors, she poured herself a glass and took a few sips. The wine tasted terrible, so she assumed it had gone bad. Later that evening, she developed severe stomach pain.
At the time, it never occurred to her that someone might have tried to poison her. But looking back, she remembered that something about the bottle had seemed unusual. It looked as though it had been opened before. Her symptoms eventually subsided, but shortly afterward, two things happened that made Nancy begin to wonder whether someone was deliberately making her sick, and whether her husband was behind it.
Back in 1989, several years before Nancy’s death, she had discovered that Richard was having an affair. She found bank statements showing that he was spending large amounts of money on gifts for another woman and on trips the two of them had taken together. Richard denied everything at first, but he eventually confessed to the affair. He and Nancy decided to try to save their marriage for the sake of their two daughters, and Richard swore that he had ended the relationship.
About a year later, Nancy learned that Richard had spent several days away with the same woman, and at that point, she decided that the marriage was over. She asked Richard to move out of the house and hired a lawyer named Mary to begin discussing the details of the divorce. Nancy also restricted Richard’s access to their joint accounts because he was continuing to spend enormous sums of money on his mistress. Nancy earned far more than Richard did, so she was the family’s primary source of income.
Without access to their joint money, he would not have been able to sustain that kind of spending on his own salary. In September of 1990, Nancy told Richard that she had made a final decision to proceed with the divorce. He accepted it at first, but over the following weeks, the two began discussing whether they should make one last attempt to save their marriage for the sake of their children. They started receiving marriage counseling and gradually began spending more time together.
Nancy and Richard went on dates, and they even traveled out of state with their two daughters to visit relatives. By the end of 1990, Richard had moved back into Nancy’s home, and the couple eventually decided not to divorce. They withdrew the divorce papers in early January, just a few days before Nancy was admitted to the hospital. By that time, Nancy had already begun to suspect that Richard might be trying to poison her.
She wasn’t entirely sure, and she didn’t want to believe that her husband was capable of such a thing, but a particular incident had made her consider the possibility. It happened after Nancy found the bottle of wine on her porch. Several weeks later, she and Richard went out on a date as part of their efforts to repair the marriage. They had dinner at a restaurant and then went to see a movie.
At the cinema, Richard brought Nancy a cup of soda, but as soon as she took a sip, she noticed a strange taste. When she looked inside the cup, she saw what appeared to be some kind of white powder in her drink. Nancy pointed it out to Richard, but he insisted that there was nothing wrong with it and repeatedly tried to convince her to keep drinking. When she refused, his anger was plain to see.
Later that night, Nancy fell severely ill again. That was the first time she seriously wondered whether Richard had put something dangerous in her drink. After Richard moved back home, Nancy continued to experience similar episodes, and they became increasingly frequent. She went to several doctors and underwent numerous tests, but no one could identify the cause of her symptoms.
Around the same time, Richard began giving her what he described as vitamins, insisting that they would help improve her health. But Nancy never saw the bottle or the packaging those capsules came from. On another evening, while Nancy was already feeling unwell, Richard brought her a drink in bed. She took a few sips, and in the middle of the night, she fell seriously ill once again.
Mary advised Nancy to bring the bottle of wine and the vitamin capsules so they could be sent to a laboratory for testing, but Nancy was hesitant. She told Mary that she did not want to accuse her husband of trying to poison her, especially without evidence. Such a scandal would cause extreme embarrassment to her family, and Nancy had been raised to believe that protecting the family’s reputation was of the utmost importance. Nevertheless, she kept both the wine bottle and the capsules, and she told Mary where they were.
As soon as Mary learned that Nancy had been hospitalized and that the doctors could not explain her condition, she called Nancy’s father and told him everything. Nancy was still alive at that point. Her father went to the hospital immediately and asked the doctors to run a toxicology test on her. He also brought them the bottle of wine and the capsules, which were then sent to a laboratory for analysis.
At that time, the doctors had already sent samples of Nancy’s blood for toxicology testing because she had told them the same story she had earlier shared with her lawyer. But such tests take time, and Nancy’s condition was deteriorating far too quickly. None of the results came back before she died. After Nancy’s death, two separate reports were filed with the police.
One came from her family after they learned what she had told her lawyer. The other came from the doctor Nancy had spoken to about her fears of being poisoned, just hours before she fell into a coma. The medical examiner performed an autopsy but found no natural cause for Nancy’s organ failure. As far as he could determine, she had no disease or medical condition that could explain her death.
So he had to wait for the results of the toxicology tests to learn more. In the meantime, experts examined the bottle of wine and the vitamin capsules that Nancy’s family had brought to the hospital. No poison was found in the wine, but the capsules told a very different story. Two of them contained barium carbonate, a toxic chemical used for industrial purposes and never intended for consumption.
That could have explained Nancy’s symptoms, but when the toxicology results came back, they revealed something entirely different. The poison in her body was arsenic, not barium carbonate. The concentration in her blood was several times higher than normal, and the medical examiner concluded that arsenic poisoning had damaged her organs and ultimately caused her death. This placed the investigators in a puzzling position.
Nancy had almost certainly been poisoned, but apparently not by the toxic substance found inside the capsules she had been taking. Once the investigators received the results, they began trying to determine when and how Nancy had been given this lethal dose of arsenic. Nancy had been experiencing intermittent episodes of illness for nearly four months before her death, including several that were particularly severe, leading the investigators to believe that someone may have poisoned her repeatedly throughout that period. To find out whether this was the case, they asked a chemistry professor to examine strands of Nancy’s hair for traces of arsenic.
The idea behind the test was simple. Hair grows outward from the roots, so the farther a section of hair was from Nancy’s scalp, the earlier a period of her life it represented. Because traces of arsenic can remain in hair, the professor was able to estimate approximately when the poison had entered her body. In the end, he identified at least three separate exposures.
The first had occurred about two and a half months before Nancy’s death. The most recent, which left the highest concentration of arsenic in her hair, appeared to have occurred about two weeks before her death. That final dose was not enough to kill her immediately, but over the following days, the poison gradually damaged her internal organs until they began to fail. By the time all these tests were completed, several weeks had already passed since Nancy’s death.
Based on what she had told her doctor and her lawyer, almost everyone close to her suspected that Richard was the one who had killed her. However, the police were careful not to identify him publicly as a suspect, and they asked Nancy’s family not to tell him that he was under investigation. The investigators did not question Richard until about a month and a half after Nancy’s death. To their surprise, they learned that he had recently returned from a vacation in Mexico with his mistress, a trip they had taken shortly after Nancy’s funeral.
Richard was asked to come to the police station, but the investigators did not initially tell him that Nancy’s death was linked to poisoning. At that time, the toxicology results were still secret even from most of her family. So the investigators began by asking more general questions. They asked Richard whether there were any chemicals in the house that Nancy might have been exposed to.
He mentioned some ant and weed killers stored in the garage, but he claimed they were harmless to humans. As the conversation continued, Richard suddenly remembered that he had ordered several chemicals the previous summer, including arsenic and cyanide. According to him, he had bought them to deal with a stubborn colony of fire ants in the yard. Richard claimed that he had not ended up using all of those materials and had disposed of them later.
The investigators then asked for permission to search his house and car without a warrant, and Richard agreed. They found no arsenic or other dangerous poisons, except for a relatively mild ant control product. The investigators also spoke with neighbors, who confirmed that the property had indeed had a serious problem with fire ants in the backyard. Nevertheless, the investigators’ suspicions toward Richard increased, and they began examining his financial records closely.
They discovered that he had placed at least three orders with a chemical supply company. In January 1990, about a year before Nancy’s death, he ordered lithium hydroxide. Then in August, he bought a long list of chemicals, including the barium carbonate that was later found inside the capsules Nancy had been taking. Finally, in late November, Richard ordered large quantities of various arsenic compounds, spending nearly 300 dollars.
Some of the packages were delivered to his workplace. However, the August shipment was sent to the apartment where Richard had been living after moving out of Nancy’s house while the two were preparing for the divorce. The investigators went to the building and spoke with one of Richard’s neighbors. The man said Richard had asked him to accept several deliveries because he would not be home when they arrived.
The neighbor did not know what was inside the packages, but he remembered seeing warnings about dangerous chemicals on the box. The investigators then asked the landlord for permission to search the apartment Richard had previously rented. Inside, they found a bag of empty capsules that could be opened and filled by hand, along with a bottle of vitamins. All of this looked highly incriminating for Richard, but the investigators did not have enough evidence to arrest him.
So they finally decided to make the investigation public, hoping that someone would come forward with additional information. In mid-March, about three months after Nancy’s death, the police held a press conference and announced that they were treating the case as a murder. They also publicly identified Richard as a possible suspect. The case immediately became a major news story.
Nancy came from a wealthy and well-known Dallas family, and the idea of a successful woman being poisoned in her own home, possibly by her husband, quickly captured the public’s attention. The very next day, Richard and his lawyer held a press conference of their own. Richard denied having anything to do with his wife’s death and continued to insist that he had bought the chemicals only to get rid of insects. He also offered several alternative explanations for what might have happened, each of which raised a new set of questions.
First, Richard said Nancy was scheduled to testify in a case against one of her former bosses, who had been accused of stealing a large sum of money. After Nancy’s involvement became known, she and a coworker received anonymous letters warning them not to interfere in the case. The coworker later told investigators that Nancy had been very nervous about testifying and had been deeply shaken by the threats. The investigators looked into this possibility and questioned Nancy’s former boss.
He denied sending the threats and claimed he had not even known those letters existed. He also pointed out that the lawsuit had eventually been resolved through a settlement between the parties, so he had no reason to kill any of the witnesses. That did not entirely eliminate suspicion of him, but the investigators could not find anything linking him to Nancy’s death. Richard’s second theory was stranger.
He suggested that Nancy might have been taking small amounts of arsenic herself to make herself sick, hoping to win his sympathy and convince him to return to married life. According to Richard, she may have accidentally taken an overdose. Finally, Richard suggested that Nancy’s older brother, Bill, might have been responsible for her death. Richard claimed that Nancy had once told him about something highly inappropriate that Bill had done to her years before.
To support his story, he handed the police a set of notes Nancy had written after her psychotherapy sessions. The notes looked more like a personal diary, and the investigators quickly noticed that many of the entries focused on Bill. In the notes, Nancy said Bill had exposed her to terrible things for years, and that she was still afraid he might hurt her to prevent her from telling anyone what had happened. She also wrote that his heavy drinking and aggressive behavior were getting worse, making her worried not only for herself but also for her two daughters.
According to Nancy, Bill was also jealous of her successful career, and he owed her about 90,000 dollars that he had borrowed from her over the years. The investigators went to speak with Nancy’s parents, and to their surprise, they admitted that some kind of inappropriate incident had indeed occurred between Nancy and Bill many years earlier. However, they insisted that it had not been as serious as Nancy described in her notes. Bill denied everything and described Nancy’s account as completely false, leaving the investigators puzzled about how to verify what she had written.
Then, while the investigation was still ongoing, the police received an anonymous letter from someone claiming to be a hired killer. The writer said Bill had paid him to kill Nancy, but after Bill failed to deliver the promised money, he had decided to tell the police everything. The investigators tried to trace the identity of the letter’s sender, but there was nothing in it that could lead them to him. It was also typewritten, so there was no handwriting to analyze, and this lead quickly hit a dead end.
After that, the investigators decided to send Nancy’s diary to a handwriting expert to confirm who had written the passages about Bill. At first, the expert found that all the entries appeared to be written in the same handwriting, including the pages that had nothing to do with Nancy’s brother. But when he compared them with other samples from both Nancy and Richard, he discovered something unusual. Their handwriting was almost identical.
According to Nancy’s family, this was no coincidence. The two had deliberately learned to write similarly during their college years because Nancy sometimes completed important assignments for Richard, and they did not want anyone to realize that someone else had written them. After studying the letters more closely, the expert found several small but consistent differences that allowed him to distinguish between Nancy’s handwriting and Richard’s. He concluded that Nancy had written most of the diary, but every paragraph about Bill had been added by Richard.
This finding gave the prosecutors what they believed was the final piece they needed, and five months after Nancy’s death, Richard was arrested. According to the prosecution, Richard had deliberately poisoned his wife with various chemicals, trying to make her death look like the result of a mysterious illness. Instead of giving her an immediately fatal dose, he was alleged to have exposed her to smaller amounts over several months, creating a history of unexplained health problems and making those around her believe she was seriously ill. As for the motive, the prosecutors believed it was something very common in such cases: money.
According to the prosecution, money was the central focus of Richard’s plan. Nancy earned far more than he did, while his own financial situation was already in disarray. If they divorced, he would lose the comfortable lifestyle her income provided, and he would likely have to pay child support for their two daughters. At the same time, Richard apparently wanted to leave Nancy and start a new life with his mistress.
The problem was that after a divorce, he would not have been able to provide her with a lifestyle comparable to what he had enjoyed while married to Nancy. That was why the prosecutors believed his sudden interest in saving the marriage had never been sincere. By convincing Nancy to stop the divorce and allow him to move back home, Richard was able to remain in line to inherit her savings and collect the 500,000 dollars from her life insurance policy. More importantly, living with her again gave him the access he needed to continue slipping chemicals into everything she consumed.
Richard’s mistress continued to stand by him, but some details in her story made him look even more suspicious. She told investigators that Richard had claimed Nancy was suffering from a rare blood disorder and would probably not live long. In reality, Nancy had never been diagnosed with such a disease, and Richard had made this comment months before her first serious illness. He had also promised his mistress that he would eventually marry her, and the relationship continued in secret even after he moved back in with Nancy and had supposedly begun trying to save his marriage.
The defense team returned to the same three theories Richard had raised at his press conference: that Nancy had been killed either by Bill or her former boss, or that she might have been taking small amounts of arsenic herself in an attempt to win Richard back. To support the last theory, Richard’s lawyers presented what initially seemed like important evidence. Richard claimed he had found an invoice among Nancy’s belongings showing that she had purchased several chemicals, including arsenic. The document even appeared to bear Nancy’s signature, making it look as though she had placed the order herself.
But the story quickly fell apart when the owner of the company named on the invoice took the stand. He explained that his company had never sold any of the chemicals listed, and that their invoices were always handwritten on completely different forms, not printed like the one Richard claimed to have found. In other words, there was no chance the invoice was genuine. Instead of helping Richard’s defense, it gave the prosecutors another reason to believe he had tried to frame Nancy.
Nevertheless, the defense made one final attempt to convince the jury that Nancy might have poisoned herself. They called a psychiatrist who had never met Nancy at any point in her life. Based only on conversations with Richard and newspaper coverage of the case, he concluded that Nancy might have suffered from psychological problems and that she might have deliberately taken poison in an attempt to win her husband back. But the prosecution had a far stronger response to this theory.
When Nancy entered the hospital and told the doctor she believed she had been poisoned, she also begged him not to let her die. If Nancy had taken the arsenic voluntarily, there would be no logic in begging the doctors to save her while refusing to tell them what she had taken. Simply naming the poison would have allowed them to begin the appropriate treatment immediately, giving her at least a chance to survive. In the end, the jury found none of the defense theories convincing, and Richard was convicted of killing Nancy.
The judge later sentenced him to life in prison and fined him 10,000 dollars. In the years that followed, Richard tried repeatedly to overturn his conviction. He first attempted to have the conviction overturned by arguing that the case against him had been entirely circumstantial. When that led nowhere, he blamed his lawyers for mishandling the trial and demanded a new one.
But in 1994, an appeals court ruled that the evidence against Richard was overwhelming, effectively ending his chances of overturning the conviction. Over the following decades, Richard continued to insist that he was innocent. He eventually reached out to several organizations that investigate wrongful convictions, but none of them agreed to take up his case. However, he did manage to attract a small group of supporters who created a website presenting the reasons they believed he had been wrongly convicted.
As for Nancy and Richard’s two daughters, they effectively lost both parents, and after Richard’s arrest, Nancy’s family took over their care. It later emerged that once Nancy had begun to suspect Richard was poisoning her, she quietly changed the beneficiary on her life insurance policy. The 500,000 dollars would now go directly to her two daughters instead of Richard, meaning that even if he had not been convicted, he would never have received the money. To this day, Richard remains in prison.
He became eligible for parole for the first time in 2006, but the board denied his request, partly because of his continued refusal to accept any responsibility for Nancy’s death. He tried again ten years later and received the same answer. His most recent attempt came in the spring of 2026, but the parole board again refused to release him, even though he is now approaching seventy years old.
At this point, there is a very strong possibility that Richard will never be released and will spend the rest of his life behind bars.
