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Crime News Accident, Suicide, or Murder

Former Nevada Physician Feeds Wife Cocktail Of Pills And Antifreeze To Kill Her

Was the doctor who did CPR on his wife the same person who poisoned her? Here's how Nevada detectives learned the truth about what happened to Susan Winters.

By Joe Dziemianowicz

Did a lawyer with two teenage daughters kill herself? Or was foul play involved?

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Las Vegas investigators faced those questions after emergency personnel raced to the Henderson, Nevada home of psychologist Dr. Gregory “Brent” Dennis and his wife Susan Winters, a 48-year-old attorney, on January 3, 2015.

After calling 911 Dennis handed the phone over to his daughter so he could frantically perform CPR, according to “Accident, Suicide or Murder,” airing Saturdays at 8/7c on Oxygen

After being rushed to the hospital, Winters, who had a DNR notice, was taken off life support and died. 

When police interviewed Dennis, he claimed that Winters believed no one loved her, saying his wife of 20 years had been depressed and suicidal.

“She says the world wouldn't care if she just checked out,” Clark County Chief Deputy DA Marc DiGiacomo told producers. 

Dennis said that he took his girls shopping to get them out of the house. When they returned at 10:30 p.m. his wife was asleep, but there was a laptop nearby. Dennis claimed he observed a search about using antifreeze to kill oneself. 

Dennis tried to rouse Winters, he said, but believed she’d been drinking. He planned to talk with her in the morning, but noted she was unresponsive. That’s when he called 911. 

He also pointed out antifreeze containers that were out of place.

His daughters’ accounts of their mother’s state of mind backed him up, said Clark County DA Investigator Jamie Honaker.

A mugshot of Brent Dennis featured on Accident, Suicide, or Murder 414

The Clark County Coroner's Office performed an autopsy to help determine if Winters’ cause of death was suicide. She had no injuries except for a mark on her nose that could have occurred during CPR. The examiner found high amounts of ethylene glycol, the main active ingredient in antifreeze, plus oxycodone and Xanax, in her system. 

Opioid intoxication and ethylene glycol poisoning were contributing causes of death. The manner of death was ruled a suicide and the case was closed by Henderson police.

However, Winters’ parents doubted that their daughter, a loving mother with a busy work life, would take her own life. Moreover, oxycodone was not prescribed to her. They hired a team of private investigators to look into the case. 

“Our objective in the beginning was just trying to find anything out of the ordinary or anything that seemed amiss,” said Henderson private investigator Lindsay Pipkins.

They immediately questioned why Dennis had his wife taken off life support so quickly. At Winters' funeral on January 9, people learned that Dennis had his wife cremated. He claimed he did it because he’d injured her nose while trying to resuscitate her. 

To investigators it raised suspicion. The team of private detectives increased their surveillance to up to 15 hours a day, seven days a week. 

They observed Dennis traveling to a “corridor that is known for sex workers and drug activity,” said Pipkins. Dennis was also covertly tailed to the Orleans Hotel and Casino, a property off the Las Vegas Strip.

He was observed taking an elevator to an upper floor and returning to his car within 10 minutes. Based on the amount of time, investigators suspected his visit involved drugs.


Private eyes found that he was going to the Orleans hotel several times during the week, sometimes twice a day. They suspected that Dennis had an expensive drug habit.

The team did a deep dive into the financial aspects of the case, learning that Winters had a insurance policy — and that Dennis had reached out to the company to make sure that it would be paid if her death was a suicide.

RELATED: Wife Poisoned Husband With Oleander, Antifreeze All For His Life Insurance Payout

The insurance company issued a check for more than $1 million to Dennis. He also drained a personal bank account that Winters had of $180,000. 

Between friends speaking of marital discord, the financial red flags, and the drug problem, Winters’ parents hoped to get the case reopened. They took the evidence acquired by the private investigators, which included recorded surveillance of Dennis doing drugs in a car in a parking lot, to a civil attorney. But they were told they needed even more “ammo.” 

Private investigators eventually determined that the individual Dennis visited in the hotel was Jeffrey Crosby, who had a prior conviction for drug trafficking. 

The civil attorney submitted a subpoena for Dennis and Winters’ computer. The search revealed that based on the timeline of events it appeared that Dennis, not Winters, searched about antifreeze.

A review of the toxicology report also raised questions about whether Winters, who had supposedly ingested painkillers, would have been physically able to go downstairs to ingest the antifreeze. 

Tony Sgro, the Winters’ attorney, filed a wrongful death suit, reported abcnews.com. It alleged that Susan Winters died under suspicious circumstances.  A year after Winters’ death, the civil trial began.

Sgro interviewed Dennis on camera. When asked if he used cocaine following his wife’s death, Dennis claimed to have no clear memory about anything. 

Dennis was unaware that private investigators documented his drug use.

“At this point, Brent is caught lying on the stand to an attorney,” said Stefanie Jay, former anchor and reporter for KVVU-TV.

Sgro stopped the proceeding and informed Dennis that he needed to get a criminal attorney, according to “Accident, Suicide or Murder.”

The Henderson Police Department officially reopened the investigation. On June 14, 2016 a new detective was assigned to the case, who focused on Dennis’ cell phone records. They showed that Dennis contacted Crosby the night Winters died and that he went to the hotel. Investigators believed that he went there to get the oxycodone pills. 

“He feeds them to her and then he watches while she slowly takes her last breath before calling 911,” said DiGiacomo. 

As the investigation continued, police learned that Dennis was actually buying medication from his patients. His drug problem had been going on for some time. Police theorized that Dennis was concerned that if he was divorced, Winters would report his drug abuse and lose his livelihood.

They believe that led him to homicide, according to “Accident, Suicide or Murder.”

After a review of the evidence the Clark County Coroner/s Office changed the cause of death from suicide to undetermined.

Dennis was arrested for murder on February 2, 2017. Eight months later, the grand jury indicted Dennis for the murder of his wife.

The proceedings were eventually interrupted by the COVID-19 pandemic but on April 29, 2022, Dennis, 59, pleaded guilty to voluntary manslaughter and using a deadly cocktail of prescription painkillers and antifreeze to fatally poison his wife, Susan Winters.

Dennis was sentenced to 36 to 120 months in the Nevada Department of Corrections. He will be eligible for parole on May 4, 2025.

To learn more about the case, watch “Accident, Suicide or Murder,” airing Saturdays at 8/7c on Oxygen.