In a gripping revelation linked to the notorious Gilgo Beach murders, Rex Heuermann, labeled as the serial killer, reportedly confessed to his former wife that he had murdered all but one of his eight victims in their Long Island residence. This shocking claim comes from a preview of the concluding episode of the Peacock documentary “The Gilgo Beach Killer: House of Secrets.”

Asa Ellerup, who completed her divorce from Heuermann last year, recounted that he admitted to the killings without hesitation, despite facing charges for only seven murders prior to pleading guilty on April 8. Her unsettling account paints a chilling picture of a man who appeared unfazed by his heinous acts.

During the preview clip, Ellerup refrained from calling him by his first name, stating, “So Mr. Heuermann, I understand that you are confessing to me about these murders – can you please tell me how many of these women did you kill?”

According to Ellerup, Heuermann responded by admitting to killing eight women. This prompted her attorney, Bob Macedonio, to question, “Eight? Who was the eighth? Because he’s charged with seven.”

Ellerup’s reply to her attorney was simple yet haunting: “I didn’t ask.” The revelation leaves a lingering question about the identity of the eighth victim, casting a deeper shadow over the already dark and complex case.

“I didn’t ask,” Ellerup replied.

Ellerup said Heuermann told her she wasn’t home at the time of the killings before Macedonio asked if any were murdered in their Massapequa Park home.

“He said yes. They were killed in his room downstairs. All except one,” she said.

“The Confession,” which is the final episode of the four-part series, will air on Peacock Thursday, and revolves around how Ellerup and his adult daughter Victoria comprehend with the admission – before Heuermann’s bombshell guilty plea.

He pleaded guilty to killing Amber Lynn Costello, 27; Megan Waterman, 22; Melissa Barthelemy, 24; and Maureen Brainard-Barnes, 25, who were famously known as the “Gilgo Four.”

He also fessed to the murders of Valerie Mack, 24; Jessica Taylor, 20; and Sandra Costilla, 28, in the case that has gripped Long Island for three decades.

Heuermann also confessed to the murder of Karen Vergeta, whose case hadn’t been linked to him.

The burly architect even copped to dismembering some of the women and tying them up in a burlap.

Heuermann’s killing spree dated back to 1993 when he picked up Costilla before strangling her and dumping her body near Fish Cove Road in Southampton. Her body was found by hunters days later.

He strangled and butchered Vergata in April 1996 after arranging to meet her. Her name wasn’t released until 2023 – 12 years after her skull was found on Ocean Parkway.

Heuermann dismembered Valerie Mack, who vanished between September and December 2000 and dumped her remains in some woods in Manorville, prosecutors said.

In July 2003, he strangled Taylor where he dismembered and dumped her body, before turning to his next victim Brianard-Barnes. 

Brianard-Barnes’ body was found in December 2010 – more than three years after Heuermann arranged a rendez-vous.

But before that discovery, he killed Barthelemy after arranging a date with her, and murdered Waterman and Costello.

Heuermann had long protested his innocence before pleading guilty. 

“This defendant walked among us playacting as a normal suburban dad when all along he was targeting these women for death,” Ray Tierney, the Suffolk District Attorney, said.

“He thought that by killing them he could silence them forever and get away with murder. But he was wrong.”

Heuermann will be sentenced on June 17.