Nancy Dillard Lyon, a 37-year-old Dallas real estate developer and mother of two, died on January 14, 1991, after her husband Richard Alan Abood Lyon poisoned her with arsenic over a period of weeks. The arsenic poisoning of Nancy Lyon became one of the most closely watched Texas murder cases of the early 1990s, both because of her family’s prominence and because Richard’s defense at trial rested on forged notes claiming dark secrets in her family. A Dallas County jury convicted him of murder in January 1992, and he is still serving a life sentence.
Who Nancy Lyon Was
Nancy was the daughter of William W. “Big Daddy” Dillard Sr. and Sue Stubbs Dillard, a wealthy Dallas family whose fortune came from commercial real estate.1Forensic Files Now. William Big Daddy Dillard She grew up in Highland Park, earned a graduate degree at the Harvard School of Design, and met Richard Lyon there. They married in 1982 and settled in a duplex in the Park Cities neighborhood of Dallas.2vLex. Lyon v. State
That same year, Nancy was hired by longtime family friend and developer Trammell Crow. She rose quickly and became a partner in one of Crow’s residential companies.3Texas Monthly. The Killer Next Door The couple had two daughters, Allison, born in 1986, and Anna, born in 1989. Richard, who came from a middle-class Connecticut family, worked as an architect and developer in Dallas.
A Marriage Headed for Divorce
By late 1989, the marriage was collapsing. Richard had begun an affair with Tami Ayn Gaisford, a coworker he met on a Saks Fifth Avenue renovation in Houston, and for Christmas 1989 he spent $4,900 of joint marital funds on a ring for her.4CaseMine. Lyon v. State, No. 08-92-00165-CR He moved out in February 1990. In June, he emptied the couple’s bank accounts and stopped paying household bills.
Nancy’s therapist, Dr. Joanna Jacobus, noted that Richard felt “trapped” by his wife’s family money and believed his in-laws considered him “inadequate.”5Encyclopedia.com. Richard Lyon Trial 1991-92 Nancy filed for divorce in September 1990 and removed Richard as the beneficiary of her $500,000 life insurance policy, naming their daughters instead.2vLex. Lyon v. State
Then the couple tried to reconcile. Nancy withdrew her divorce petition on January 2, 1991. She was dead twelve days later.5Encyclopedia.com. Richard Lyon Trial 1991-92
The Poisonings Before the Fatal Dose
The fatal dose was not the first. In September 1990, Nancy found a bottle of wine with an anonymous card on her porch; the cork looked tampered with, and after drinking some she became violently nauseous.2vLex. Lyon v. State On another occasion Richard bought her a soft drink at a movie theater. She spat it out after tasting something foul, noticed a white powder floating on the surface, and spent that night vomiting.4CaseMine. Lyon v. State, No. 08-92-00165-CR
Richard had also been giving Nancy what he described as vitamin capsules, encouraging her to take them for her health. She became severely ill on a ski trip to Colorado in December 1990. She confided to her divorce attorney, Mary Henrich, that she believed Richard was “systematically poisoning her.”6JRank Law. Richard Lyon Trial 1991-92 – Marriage on the Rocks Henrich urged her to have the wine tested, but Nancy declined, saying it would be embarrassing to accuse her husband.3Texas Monthly. The Killer Next Door
Death at Presbyterian Hospital
On the evening of January 8, 1991, Nancy became acutely ill. She was admitted to the emergency room at Presbyterian Hospital in Dallas at roughly 1:50 a.m. on January 9 with uncontrollable vomiting, nausea, and diarrhea.3Texas Monthly. The Killer Next Door Doctors initially suspected toxic shock or food poisoning.
Her father Bill Dillard arrived at the hospital on January 10 and told a resident he suspected Richard was poisoning his daughter. Nancy herself corroborated those fears to Dr. Ali Bagheri, describing the wine, the soft drink, and the vitamin capsules.2vLex. Lyon v. State Bagheri later testified that he waited to speak with her alone, after Richard left her bedside, and that she pleaded: “Please help me. Help me. Don’t let me die.”3Texas Monthly. The Killer Next Door
Her condition worsened quickly: racing pulse, dangerously low blood pressure, lung failure. She was sedated and placed on a respirator. On January 14, 1991, she was removed from life support and died at approximately 3:30 p.m.2vLex. Lyon v. State Richard made the decision to terminate life support without consulting her parents.1Forensic Files Now. William Big Daddy Dillard
What the Autopsy and Lab Work Showed
An autopsy performed on January 15, 1991, by the Dallas County medical examiner confirmed the cause of death as arsenic poisoning and ruled it a homicide.3Texas Monthly. The Killer Next Door Nancy’s blood contained between 4 and 100 times the normal level of arsenic, and her liver, kidneys, fingernails, and hair all showed markedly elevated concentrations.4CaseMine. Lyon v. State, No. 08-92-00165-CR
Toxicologist James C. Garriott used neutron activation analysis of Nancy’s hair to identify two distinct arsenic exposures: one fatal dose and a separate exposure two to five weeks earlier. Another expert, Vincent P. Guinn, identified three exposures altogether — a minor one about seven to ten weeks before death, a mid-level dose two to five weeks prior, and what he called a “tremendously high” exposure roughly two to two and a half weeks before she died.4CaseMine. Lyon v. State, No. 08-92-00165-CR Her fingernail clippings contained six times more arsenic than her toenail clippings, suggesting she had been handling arsenic, possibly through the capsules she was given.
Analysis of those vitamin capsules revealed that two of the sixteen pills contained pure barium carbonate, a substance that can be lethal in sufficient quantities.2vLex. Lyon v. State A separate prescription bottle of Keflex found in the home contained capsules filled with sodium nitroferrocyanide, a compound that can produce cyanide.4CaseMine. Lyon v. State, No. 08-92-00165-CR
How Investigators Tied Richard to the Chemicals
Detective Don S. Ortega of the Dallas Police Department homicide unit led the investigation and deliberately waited nearly two months before questioning Richard.3Texas Monthly. The Killer Next Door The break came from the Dillard family, who handed over a canceled check Richard had written to General Laboratory Supply in Pasadena, Texas. Ortega subpoenaed Richard’s bank records and the supplier’s files.
Rose Ellen Rose, an operations manager at the supply company, confirmed three orders from Richard:
- January 1990: 100 grams of lithium hydroxide monobasic.
- August 1990: barium carbonate, cyanogen bromide, lead nitrate, and nitroferrocyanide.
- November 1990: a larger order including arsenic trioxide, arsenic standard, Congo red, and other chemicals, totaling $270.45. Richard wrote “fire ant poison” on the check.
The November order was delivered to Richard’s office on December 27, 1990, and signed for by a receptionist.4CaseMine. Lyon v. State, No. 08-92-00165-CR
Ortega interviewed Richard on February 27, 1991. Asked whether he had bought chemicals, Richard said no. Pressed, he admitted to buying mercury, lead, cyanide, and “arsenic acid” but insisted he had thrown them all in the trash and used them only for fire ants. In the 44 days since Nancy’s death, Richard had never once contacted the medical examiner’s office to ask about the cause of death. When Ortega told him Nancy had been poisoned, Richard showed no visible reaction. “Right then, I knew I’d found my suspect,” Ortega later testified. “He lied to me, and I let him lie to me.”3Texas Monthly. The Killer Next Door
A search of Richard’s duplex and car turned up no trace of the chemicals. The contaminated pills already in Nancy’s possession supplied the direct link.
The Trial and the Forged Notes
Richard was arrested in May 1991 and charged with first-degree murder. His trial took place in December 1991 before Judge John C. Creuzot in Dallas County.7Forensic Files Now. Nancy Dillard Lyon
Prosecutors argued that Richard had systematically poisoned Nancy over months, driven by the failing marriage, his affair with Gaisford, and money. They presented the chemical purchase trail, the forensic analysis of the pills and tissue samples, and testimony from Nancy’s physicians and her divorce attorney about her belief that Richard was poisoning her. Dr. Bagheri testified that Richard’s demeanor in the emergency room, while his wife was gravely ill, was “inappropriate” — he appeared to be smiling, laughing, and joking.2vLex. Lyon v. State Tami Gaisford testified that Richard had told her Nancy died from a “rare fatal blood disease.”8Forensic Files Now. Richard Lyon
The defense introduced handwritten notes that appeared to be in Nancy’s writing, alleging her brother Bill Junior had sexually abused her for years and referring to “sick sex, incest issues with me, my girls.”4CaseMine. Lyon v. State, No. 08-92-00165-CR Defense experts, psychologist Robert Geffner and psychiatrist James P. Grigson, testified that Nancy was a troubled incest survivor, “calculating, controlling, and manipulative,” and suggested she may have poisoned herself.
The rebuttal broke that theory. Document examiner Hartford R. Kittel testified that while parts of the notes were in Nancy’s handwriting, the most incriminating passages, those referencing “fear of reprisal,” “sex,” “sick sex,” and “incestuous,” were written by Richard. A note claiming Bill Junior had “violated her for years” was entirely in Richard’s handwriting.4CaseMine. Lyon v. State, No. 08-92-00165-CR Nancy’s close friend Amy William Monier testified that Nancy had never mentioned any incestuous relationship with her brother.
In January 1992, the jury convicted Richard Lyon of murder. He was sentenced to life in prison and fined $10,000.4CaseMine. Lyon v. State, No. 08-92-00165-CR His conviction was affirmed on appeal on December 21, 1994.
What Happened to the Daughters
After Richard was sent to prison, Allison and Anna were raised by the Dillard family and took the surname Dillard.9Forensic Files Now. Richard Lyon William Dillard died in 2006, and Sue Dillard died in 2009.1Forensic Files Now. William Big Daddy Dillard
Where Richard Lyon Is Now
Richard Lyon became eligible for parole in December 2006 and has been denied every time.10Texas Department of Criminal Justice. Offender Information – Lyon, Richard Alan Abood The Texas Board of Pardons and Paroles turned him down in 2006, on February 3, 2016, on March 1, 2021, and again on March 23, 2026.11Texas Department of Criminal Justice. Parole Review Information – Lyon, Richard Alan Abood The board has repeatedly cited the nature of the offense, noting elements of brutality, violence, assaultive behavior, or conscious selection of the victim’s vulnerability, and has consistently determined that Lyon “poses a continuing threat to public safety.” His next parole review is scheduled for March 2030.
Lyon maintains his innocence. He has sought help from the Innocence Project of Texas, the Innocence Project of New York, the Thurgood Marshall School of Law Innocence Project, and the House of Renewed Hope. All have declined to take his case.7Forensic Files Now. Nancy Dillard Lyon He remains incarcerated at the Ramsey I Unit in Texas.