Gilgo Beach killer Rex Heuermann had a ‘Dexter’-style murder chamber at home

RIVERHEAD, NY – Rex Heuermann, who will spend the rest of his life in prison after pleading guilty to being the Gilgo Beach killer, had a “Dexter” murder chamber in his basement, according to the top prosecutor in the case.

“That’s very upsetting, and I think when we saw what it was, you know, that was some of the words that were said,” said Suffolk County District Attorney Ray Tierney, who was part of the prosecution team that secured Heuermann’s guilty plea. “We were actually able to recreate that, in the basement, on location.”

And that’s the room where Heuermann’s ex-wife now sleeps, according to a new documentary, “The Gilgo Beach Killer: House of Secrets,” in which she claims.

Heuermann received the maximum sentence from Judge Timothy Mazzei on Wednesday – three consecutive life terms without the possibility of parole, followed by four consecutive terms of 25 years in prison.

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“You are a disgusting and despicable little man, if you are a man,” Mazzei told the defendant. “And he is a coward.”

After a while, he told court officials to “get him out of here.”

Heuermann is expected to be in state prison before the end of the week, Tierney said.

So he took that book, not to gain insight, but to become a better killer, especially to avoid getting caught.

In an interview with Fox News and Fox News Digital after the sentencing hearing, Tierney explained why investigators returned to Heuermann’s basement long after arresting him and spent days searching the house.

They found a deleted document that Heuermann wrote “HK,” which Tierney said stood for “hunt-kill.” Although Heuermann made and removed many versions of it over time, the investigators were able to find only one.

Prosecutors described it as a planning document. He mentioned the places where the traffic cameras go to and from the places where they dump the bodies of the victims. He wrote down the things he would need for the kill and reminded himself to rest well and remember to cry.

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Gilgo killer Rex Heuermann walks into court to be sentenced at the Suffolk County Courthouse in Riverhead, NY, on June 16, 2026. (James Carbone/Newsday)

He also discussed the merits of using tape vs. pins to hang clothes in the basement where he is believed to have killed seven of the eight.

“He was hanging plastic from the ceiling and the walls,” said the district attorney. “That’s what the text says, and then it says don’t use push pins, because they damage the ceiling. Use tape.”

When the detectives returned home with infrared and ultraviolet lights, they found more evidence.

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“We saw adhesive stains on the wall,” Tierney said. “And then what we’re able to do is we’re able to see that they’re making a perfect square – and that’s where, we believe, the crime is happening.”

Heuermann, described as an “ogre” by the only eyewitness in the case, stands about 6 feet 4 inches tall and weighs about 300 pounds. The victims were 5 meters tall and 100 kilograms, and in the text “HK”, he noted that “smaller is better.”

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The victims were Sandra Costilla, 28, who was found in the North Sea; Karen Vergata, 34, was found on Fire Island near Tobay Beach; Valerie Mack, 24, was found at Manorville and Ocean Parkway near Gilgo Beach; Jessica Taylor, 20, was found at Manorville and Ocean Parkway – along with the so-called Gilgo Four, all found east of Gilgo Beach on the north side of Ocean Parkway. They were Maureen Brainard-Barnes, 25; Melissa Barthelemy, 24; Megan Waterman, 22; and Amber Lynn Costello, 27.

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Rex Heuermann appears in a booking photo released by authorities. He was sentenced to life in prison without parole after pleading guilty to seven counts of first-degree murder and an eighth count of first-degree murder. (Suffolk County District Attorney’s Office)

Investigators believe Heuermann’s only known murder since Costilla’s 1993 murder was when Costello disappeared in 2010.

Before Heuermann was sentenced, relatives of his victims gave emotional statements about the decades of pain and loss the killings left behind.

Mack’s adoptive parents were among the first to speak in court. Her father told Heuermann that despite the violence of her crimes, “it never touched her soul,” adding that “Valerie is the one who is free today, and you are not.”

Taylor’s relatives recounted the heartbreak of discovering that only her remains were initially found and the pain of seeing the case repeatedly return to public attention over the years. Another cousin mocked Heuermann’s attempts to evade arrest, telling him that he made elaborate plans to escape the murder charge but left behind evidence that led investigators to him.

The most touching testimony came from the family of Brainard-Barnes, one of the so-called Gilgo Four. His sister, Melissa Cann, remembers the last conversation they had before Brainard-Barnes disappeared.

“The last words he said to me were, ‘I love you. I’ll see you tomorrow,'” Cann told the court.

Cann explained the survivor’s years of guilt and said he was dedicated to helping the killer be finally identified and brought to justice.

Brainard-Barnes’ daughter, Nicolette, said she was only 7 years old when her mother was killed and is now older than her mother was when she died. He said the victims are “more important” than Heuermann and described him as “a coward who exposes his shortcomings to others.”

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Rex A. Heuermann pleads guilty to the murders of seven women and pleads guilty to an eighth count during a hearing in Suffolk County Court in Riverhead, NY, on April 8, 2026. (James Carbone/Newsday via Pool)

Heuermann pleaded guilty to seven counts of murder on April 8 and admitted to Vergata’s 1996 murder, for which he was not charged.

Asked if there might be more victims, Tierney declined to speculate. He said if the evidence shows that there is, he will bring it to the high court and seek a new charge.

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He pointed out that prosecutors have additional evidence against Heuermann that has not been made public and explained how Heuermann evolved over the years from a “disorganized” killer to a “organized” one.

Tierney said Heuermann appeared to be very disorganized early in his criminal career before becoming more methodical and deliberate over time, as evidenced by a log book, his progressive work style and digital evidence that showed he scanned news reports for updates on the murders he had committed.

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At one point, he also picked up the book “Mindhunter” by the famous FBI analyst John Douglas.

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“When you’re a high school football player and you get, Peyton Manning’s book, you want to be a better quarterback,” he said. So he took that book, not to gain insight, but to become a better killer, especially to avoid getting caught.“

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As part of the plea deal, Heuermann agreed to sit down with the FBI’s Behavioral Analysis Unit for a clinical evaluation, Tierney said. Douglas, the inventor of criminal profiling, was formerly the chief of the FBI’s Behavior Science Unit, the predecessor of the BAU.

“That was my suggestion,” Tierney said. “I was a former federal prosecutor. I know the work of the BAU. I know I knew about this defendant’s ‘Mindhunter’ book. I knew that was something he was interested in, so I thought it would be a good opportunity.”

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Investigators can learn from Heuermann in the clinical setting and use the knowledge to help with new cases as they arise, he said.

Fox News’ CB Cotton and Kirill Clark contributed to this report.