The Dateline episode on Susan Winters, “A Cool Desert Morning,” told the story of a 48-year-old Nevada attorney and part-time judge who died on January 3, 2015, from a lethal mix of antifreeze and oxycodone. Police first called it suicide. Her parents refused to accept that, funded a private investigation, and eventually pushed prosecutors to charge her husband, psychologist Gregory “Brent” Dennis, with murder. Dennis entered an Alford plea to voluntary manslaughter in 2022 and was sentenced to three to ten years in prison. Correspondent Josh Mankiewicz reported the episode, which first aired on October 11, 2022.
Who Susan Winters Was
Winters lived in Henderson, a Las Vegas suburb, where she practiced law and served as a part-time judge in North Las Vegas. She also held an ownership interest in her family’s Sonic hamburger franchises, which brought her roughly $200,000 a year. She and Dennis were high school classmates who reconnected after both had divorced, married in 1995, and had two daughters together. Dennis was a licensed psychologist with a doctorate from the University of Tulsa and a private practice in the Las Vegas area.
How She Died
Winters was found unconscious at her Henderson home on the morning of January 3, 2015, and later taken off life support at the hospital. The Clark County coroner’s office determined she died from ethylene glycol, the active ingredient in antifreeze, combined with oxycodone. She had no prescription for oxycodone, and no bottle of the drug was recovered at the scene.
Dennis told first responders that his wife suffered from depression and anxiety and had threatened suicide before. He pointed officers to internet searches on the family computer about antifreeze poisoning and to two bottles of antifreeze in the garage. On his account, the Henderson Police Department and the coroner’s office ruled the death a suicide and closed the case.
How Her Parents Reopened the Case
Susan’s parents, Danny and Avis Winters, rejected the suicide ruling from the start. They said their daughter had been in good spirits, was planning for the new year, and adored her daughters. Danny Winters pointed out that antifreeze poisoning causes days of excruciating pain, making it an implausible method of self-harm. The family also noted the scene lacked pill bottles or poison containers near Susan’s body.
Using their resources as principal owners of the Sonic franchise chain, the Winters family hired retired FBI agent James Perry as a private investigator and retained attorneys Tony Sgro and David Roger, a former Clark County district attorney. Roger and Perry produced a 49-page report laying out possible motives for Dennis to have killed his wife.
They also sued Dennis in civil court over the distribution of Susan’s roughly $2 million estate. That case gave Sgro the power to subpoena banking records and cell phone data and to depose Dennis under oath. In a videotaped deposition, Dennis admitted paying cash for controlled substances from Jeffrey Crosby, a convicted drug dealer.
The Evidence That Pointed to Dennis
The private investigation and civil discovery produced a series of findings that contradicted the suicide theory.
- Surveillance showed Dennis had been visiting The Orleans casino in Las Vegas several times a week for about a year to buy cocaine, methamphetamine, and oxycodone from Crosby. Phone records logged more than 3,900 contacts between the two men over 13 months.
- The final antifreeze-related computer search was made at 5:15 a.m. on the morning Susan died, when investigators concluded she was already unconscious and could not have used the computer herself.
- Cell phone records placed Dennis at The Orleans meeting Crosby during hours he claimed to have been asleep at home while his wife was dying.
- Dennis did not call 911 until 6:45 a.m., roughly an hour and a half after the final computer search. Prosecutors later alleged he “waited for her to stop breathing.”
- Dennis stood to inherit about $2 million, including a $1 million life insurance policy. He filed the insurance claim at 9:30 a.m. on the first business day after Susan’s Saturday death and deposited a $180,000 check drawn on an account only she could access. Prosecutor Marc DiGiacomo later said Dennis told a friend he moved the money because “he knew that when she died that her parents would freeze that account.”
- According to the arrest report, Susan had enough antifreeze in her system to “kill her twice over,” along with a separately lethal amount of oxycodone. The antifreeze bottles in the garage were manufactured in 1997 and 2007, before a 2013 industry reformulation added a bitter taste to prevent poisoning. The older formula tasted sweet and could be masked in food or drink.
- Phone records and family testimony indicated that in the days before her death, Susan had confronted Dennis about his drug use and told her parents she planned to report him to the Nevada psychology board.
Sgro summed up the family’s conclusion: “Everything that we learned seemed to point towards foul play. Nothing we learned tended to point toward Susan taking her own life.”
Charges, Plea, and Sentence
Clark County prosecutor Marc DiGiacomo officially reopened the case in the summer of 2016. Henderson police arrested Crosby at The Orleans that July, and he was indicted for trafficking in cocaine. On February 2, 2017, Henderson police arrested Dennis on a charge of open murder with a deadly weapon. Five days later, the Nevada Board of Psychological Examiners summarily suspended his license. On April 3, 2017, Clark County Coroner John Fudenberg changed Susan’s manner of death from “suicide” to “undetermined,” citing additional evidence from police.
The case moved slowly. DiGiacomo called it “highly complex with a lot of circumstantial pieces of evidence.” In January 2022, Dennis entered an Alford plea to a reduced charge of voluntary manslaughter, a plea that lets a defendant maintain innocence while conceding prosecutors have enough evidence to convict. Defense attorney Richard Schonfeld said Dennis took the deal to spare his daughters a trial.
On May 10, 2022, District Judge Michelle Leavitt sentenced Dennis to three to ten years in the Nevada Department of Corrections. Susan’s mother, Avis Winters, told the court: “As if losing Susan wasn’t enough, we also lost the relationship we had with her daughters because we never believed this case was anything other than a murder case. The sadness is overwhelming at times.” Susan’s best friend, Natalie Tyrrell, called the case “the ruination of a family.”
Dennis’s two daughters supported their father. In a statement read by Schonfeld, they said they had agreed to the plea “not because we believe for a second that he had any involvement in our mother’s death,” but to put the case behind the family. DiGiacomo framed the outcome as pragmatic: “I’m looking at a 60-year-old man, and what is justice.”
Where Dennis Is Now
In 2023, a civil court found Dennis liable for Susan’s wrongful death and ordered him to pay her family just over $1 million. The Winters family had earlier bought back Susan’s shares in the family restaurant business from Dennis for roughly $700,000.
Dennis was assigned to Indian Springs Conservation Camp, a minimum-security facility in the Nevada corrections system. A Nevada Department of Corrections parole eligibility report generated in December 2024 listed him (NDOC ID 0001257013) as still incarcerated, eligible for a parole hearing in February 2025, with a parole eligibility date of May 4, 2025.