Susan Winters' murder: A complete timeline of events
Susan Winters was a 48-year-old woman who was rushed to the hospital from her Las Vegas residence on January 3, 2015. The doctors found that Susan had ingested a lethal dose of oxycodone, mixed with antifreeze.
Susan Winters was put on life support, but she died the next day. Susan's husband, Dr. Gregory Dennis, called 911 emergency, and then handed the phone to his daughter. The daughter revealed that Dennis was performing CPR on his wife. Dennis told the authorities that his wife had depression, which led to her suicide.
Initially, the case was closed, considering the death to be a case of suicide. However, Susan's parents hired a team of private investigators. When Dennis was kept under surveillance, they soon discovered that Susan's husband was involved in her death.
The Dateline episode this week, titled A Cool Desert Morning, explores the complete investigation behind the murder of Susan Winters. The episode released on April 18, 2025, at 9 pm on NBC.
What happened to Susan Winters?
As reported by Oxygen, Susan Winters was married to Dr. Gregory Dennis, who worked as a psychologist. It was on January 3, 2015, that Dennis called 911. His daughter reported that her mother was unresponsive at her apartment, and Dennis was providing her CPR.
Susan Winters was immediately rushed to the hospital, where she died the next day. As reported by ABC News, after the autopsy, the Clark County Coroner's Office revealed that Susan died due to the combination of ethylene glycol and oxycodone poisoning.
As per Oxygen, when authorities interrogated Dennis at the crime scene, he revealed that he was suffering from depression and had suicidal tendencies. As per Dennis' story, he went out with the girls for shopping. It was 10:30 pm when they reached the residence and saw Susan in a sleeping position, with her laptop next to her.
Dennis added that when he tried to wake her up, she was unresponsive. At the crime scene, Dennis pointed to the spilled containers of antifreeze, indicating that she died due to intoxication.
Reportedly, the body of Susan Winters didn't have any visible injuries, except for a scar on the nose. The authorities concluded that it was created while Dennis was doing CPR. The victim's topological reports revealed that Susan had high amounts of ethylene glycol in her system, along with Xanax and oxycodone.
As per Oxygen, ethylene glycol was the main ingredient found in antifreeze. Without any more concrete evidence to follow up, the case was closed, declaring it to be a suicide.
Susan Winters hired private investigators to continue the investigation
As reported by Oxygen, after the case was closed by Henderson police, the victim's family hired a team of private investigators to continue with the case. Private Investigator Lindsay Pipkins revealed that their prime mission was to find any suspicious elements regarding the case.
Dr. Gregory Dennis was brought in for interrogation, and he was asked why he took off Susan's life support the very next day. Additionally, Dennis cremated his wife's body at her funeral.
Dennis replied that it was due to the injury he caused to his wife's nose while providing CPR. The answers provided by Dennis caused more suspicion about his involvement in the crime. As a result, a team of investigators kept him under surveillance.
As reported by Oxygen, the investigators followed him to the Orleans Hotel and Casino in Las Vegas. Reportedly, the region was infamous for s*x workers and drugs. Investigators soon suspected that Dennis Winters was involved in drugs, after he was seen visiting the same place multiple times a week.
When investigators looked into the bank profile of the suspect, it was revealed that Susan had a life insurance on her name, where the money would only be received after the subject had died of suicide.
Reportedly, Dennis took out all the money from one of Susan's bank accounts, which had $180,000.
As reported by KTNV, Dennis received a sum of almost $2 million from the life insurance company. As reported by Oxygen, the private investigators recorded a video of Dennis doing drugs in a parking lot, which was provided to the jury.
As per Oxygen, while going through Dennis' search history, investigators discovered him searching for Antifreeze. Additionally, it was revealed that Dennis often went to to Orleans Hotel and Casino in Las Vegas, to meet a man named Jeffrey Crosby, who was connected to drug trafficking.
With the new set of evidence, the case of Susan Winters was reopened by the Henderson Police Department. It was on June 14, 2016, when a new detective was assigned, who went through Dr. Gregory Dennis' call records.
It was revealed that on the night Susan Winters was found unconscious, Dennis had contacted Crosby in the hotel. As per the investigators, Dennis bought oxycodone pills from him, which he fed to Susan.
Investigators claimed that Dennis murdered Susan Winters with the oxycodone pills, and then called 911 to prevent any suspicion. Authorities believed that Dennis had a strained marriage, and Susan knew about his drug consumption.
According to Oxygen, it was on February 2, 2017, when Dr. Gregory Dennis was arrested by the police. Eight months later, the case was presented before the jury. As reported by KTNV, Susan had confronted her husband about his drug abuse and threatened to report it to the state licensing board.
As reported by Oxygen, it was on April 29, 2022, when Gregory Dennis was found guilty of voluntary manslaughter and use of a combination of painkillers and antifreeze to murder Susan Winters.
He received a sentencing of 36 to 120 months imprisonment and was sent to the Nevada Department of Corrections. Reportedly, the Dateline culprit will be eligible for parole on May 4, 2025.
Check out our other articles to learn more details on Dateline's episode titled A Cool Desert Morning.
