Gilgo Beach serial killer Rex Heuermann had 4-day killing ritual to keep secret life hidden, documentary reveals

Long Island serial killer Rex A. Heuermann maintained a four-day killing ritual, building trust with his victims before ending their lives in a basement "kill room" and dumping their remains near Gilgo Beach, a therapist reveals in a grisly new documentary episode streaming Thursday.

By the time Heuermann killed what he says was his eighth and final victim, the practice became so routine his stopwatch informed him it took just 37 seconds to dispose of the remains of Amber Lynn Costello along the north side of Ocean Parkway in September 2010, Sayville therapist Alison Winter discloses in the final installment of Peacock’s "Gilgo Beach Serial Killer: House of Secrets."

"He would hit the timer, dump the body, get back in the truck and hit the timer again," said Winter, who participated in the series after Heuermann and his family waived their rights to patient privacy. "Clearly, he enjoyed killing and it became a sickness for him. It became an outlet. It became an obsession."

The documentary exposes buried details of how Heuermann refined his killing methods — from adolescent urges to an unplanned murder inside his vehicle, to seven calculated slayings in his Massapequa Park home — as he methodically planned his kills in an effort to keep his secret life hidden from his family and authorities. Thursday's episode provides the closest look yet into the mind of one of Long Island's most prolific serial killers, never slamming shut the notion that his final death count could be greater than already known.

An open book

Winter and the ex-wife and daughter of Heuermann told the filmmakers he privately confessed to them in a series of meetings at the Suffolk County jail in Riverhead last summer, sharing chilling insights not previously disclosed.

The secret meetings were a condition Heuermann, who publicly admitted eight killings earlier this month, demanded in his plea agreement, family attorney Robert Macedonio, of Islip Terrace, disclosed in the 85-minute episode. The episode, the last of four, blends blockbuster revelations about an infamous case that haunted Long Island for 17 years with made-for-television moments like the opportunity to hear from the killer himself.

"It was something that we needed to do face-to-face and be honest with each other," Heuermann said of the meetings in one of several jail calls timed for when the documentary crew was filming at the family home. "It needed to be done person-to-person, heart-to-heart."

The killer said he was an "open book" in the meetings with his family, who were reportedly paid more than $1 million for access to their First Avenue home and lives. Heuermann had publicly denied any involvement in the killings from his arrest in July 2023 to his guilty plea April 8. 

Thursday’s episode reveals Heuermann privately confessed to his attorneys in spring 2025; filming for the fourth episode began soon after.

Defense attorney Michael J. Brown, of Central Islip, and Suffolk County District Attorney Ray Tierney did not respond to messages seeking comment Wednesday. It was unclear if either had seen the episode in advance of its premiere.

As part of the agreement, Heuermann will be sentenced to multiple life prison sentences by State Supreme Court Justice Timothy Mazzei on June 17.

Ex-wife sleeps in 'kill room'

Winter attended the jail meetings between the 62-year-old former Manhattan architect and his second wife, Asa Ellerup, also 62, and their daughter, Victoria Heuermann, 29. Winter said Rex Heuermann told his wife that he did not intend to kill Sandra Costilla, his first victim, but ultimately murdered her outside the family home, an apparent rare and impulsive act for a man who coolly chronicled how he methodically plotted the killing of each of the other seven victims. The Queens woman was killed in November 1993 inside his Dodge Ramcharger, Ellerup said. Victoria Heuermann recalled the family driving around in the truck in the years that followed. 

Victoria Heuermann said victims Karen Vergata, Valerie Mack and Jessica Taylor were all "murdered, mutilated and dismembered" in her father’s private "kill room" in the basement of the family home, where Ellerup revealed she now sleeps each night. One of the other killings — either Costello, Melissa Barthelemy, Maureen Brainard-Barnes or Megan Waterman — took place in the bedroom Heuermann shared with Ellerup at the time, the daughter said her father confirmed.

Winter said Heuermann told her he paid for sex with his victims, before arranging a second meeting, beginning his four-day ritual with his family away on vacation each time.

'A four-day high'

As part of his carefully planned sequence, he spent the first day cleaning his basement and preparing to spend the following day with the women, the therapist said. He would display a friendly demeanor with each woman until he was ready to kill. After killing them, he engaged in what he described as "playtime" with their dead bodies before dumping their remains, usually in the Gilgo Beach area. Prosecutors have said some of his victims suffered postmortem wounds and have pointed to references to "playtime," "torture," "captivity" and "noise control" in a planning document he maintained as evidence of his intent with victims.

He spent the third day cleaning up and disposing of any tools and materials used in the crime, Winter said. After his arrest, authorities painstakingly gathered evidence from the home, but it's unknown whether the public will ever see the full extent of what was gathered following the plea agreement.

Heuermann kept the fourth day open for emergencies, Winter said.

"It’s a four-day high," the therapist said. "A four-day adrenaline rush and then he would [meet] his family."

Heuermann told Winter it took him 2 minutes, 32 seconds to go from his truck to the sandy grave and back the first time he dumped a body at Gilgo Beach.

He knows because he timed each one, he told Winter. The more he killed, the faster he got at disposing of remains, trimming the time to 37 seconds in his final confessed killing.

Why he said he stopped killing

On their 12th session together, Heuermann discussed his childhood with the therapist, she said. Ellerup refuted tabloid headlines that described the killer as having "mommy issues." His father’s domineering personality and sudden death at age 50, when Heuermann was 12 years old, were offered in the documentary as alternative possible reasons for how he grew into a methodical killer.

Winter said Heuermann’s "unhealthy thoughts" began when he was a student at Massapequa High School in the late 1970s and early 1980s. He consumed violent pornography and books about death and the dissection of the human body at a young age, she said. Heuermann told her he never had a healthy sexual experience.

"Clearly he enjoyed killing and it became a sickness for him," Winter told the filmmakers. "It became an outlet. It became an obsession."

Heuermann told Winter the killings stopped in September 2010 because he was no longer receiving the same gratification. The therapist said she pushed back on that theory, noting just three months later the search for missing Shannan Gilbert led police to find the first four sets of remains along Ocean Parkway.

"I think he was very concerned about getting caught, and I think he knew he would get caught," Winter told the filmmakers.

Did not see victims as human

The documentary leaves open the idea Heuermann is responsible for more killings.

Victoria Heuermann said she doesn’t know if she believes her father killed only the eight women he has publicly confessed to murdering.

He told her he did not see the victims as "human" and that they provided him with an opportunity to act out his sadistic impulses. His "demons got to him," Victoria said of her father’s description of the killings.

"When he was in a certain opportunity, or there was a certain catalyst in front of him, that would start to create these dark urges," the daughter said.

Victoria Heuermann said her father also disclosed he twice took photographs of the killings that were long ago destroyed. She said a planning document he had maintained, which prosecutors called a key piece of evidence in their case against him, was first created as a "way to distract himself from actually having to do the act itself."

"If he puts it on paper and acts it out in his head, that would curb the urge," Victoria Heuermann recalled her father saying.

Asked in a jail call about his meeting with Victoria, Heuermann said it was "difficult to go into details."

"There’s such an array of mixed emotions," the killer said.

Victoria Heuermann said the meetings were scheduled months before the plea to give the family time to heal before his public confession. Ellerup said she agreed to meet with her ex-husband because she wanted to hear the truth. She has met with him several times since, she said.

"I want to hear it from his mouth," she told Macedonio and Winter near the start of the episode.

Ellerup said Heuermann looked nervous and cried when he confessed to her. He was not remorseful for the killings, only for destroying his family, she said.

"I think the tears were for me," Ellerup said.

'He would have killed more'

Famed FBI profiler John Douglas, a pioneer of the bureau’s Behavioral Analysis Unit that will soon interview Heuermann as part of his plea agreement, met with Winter and shared his perspective on the killer in a later scene.

Douglas said he doesn’t believe Heuermann began killing at 30 years old and said the death penalty may be preventing him from admitting to more killings in other states, pointing to property Heuermann owned in South Carolina, a capital punishment state.

"I think he has a lot of hidden secrets," Douglas told Winter. "He’s a malignant, narcissistic, sadistic, psychopathic serial killer. Had he not been apprehended, I think he would have killed more."

Winter told the filmmakers Heuermann greeted her during her first visit to the county jail by asking if she "ever sat with a serial killer before." He also asked the therapist if she knows what it’s like to want to kill someone, "to play God," she recalled.

Heuermann’s recent confession to killing Vergata, for whom he was never charged with murder, was not known as the filmmakers began filming the fourth episode. Three earlier entries into the series were released in June 2025.

Winter said the April 1996 murder of Vergata, who was killed days before Heuermann and Ellerup were married in Sweden, was a "pivot point" for him to get comfortable with killing while embarking on family life. He described being a husband and a killer as "two separate entities," the licensed social worker told the filmmakers.

"It became more of a game inside his mind," Winter said. "Prepping, timing, playtime, cleanup. It all became a methodical second life."

The series closes with Ellerup disclosing she has renovated Heuermann’s former "kill room," which was next to a gun vault in their basement, into a bedroom for herself. She is seen in the final moments thumbing through photographs of his victims while sitting on her bed in the tragic space.

"I’m here because I do feel spiritual," Ellerup said. "I am trying to say, spiritually in my own way, that I am really sorry for what these victims went through."