Rex Heuermann, the man who admitted to killing eight women whose remains were found along Long Island’s Gilgo Beach, told his former wife he killed seven of those victims in their Massapequa Park home, a preview of “The Gilgo Beach Killer: House of Secrets” revealed.

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In a preview of the final episode of the Peacock documentary series about the slayings — which airs Thursday — Heuermann’s ex-wife, Asa Ellerup, said he told her he killed eight of the women who were found along Gilgo Beach.

“He said he killed eight women,” Ellerup said in the clip. She said there was no hesitation when Heuermann made the admission, but that he was very nervous when they were speaking.

Heuermann, 62, was charged with killing seven of the women whose remains were found more than a decade ago on Long Island’s south shore, but confessed he killed an eighth — Karen Vergata — when he took a plea deal April 8.

He changed his plea from not guilty to guilty in a New York courtroom earlier this month. In exchange for the admission, Heuermann will not face charges in the death of Vergata, who disappeared in 1996.

In court, he admitted to meeting all eight women, strangling them and dumping their bodies where they were found across Gilgo Beach, Manorville and Southampton.

Heuermann also agreed to cooperate with the FBI as a part of the plea agreement, but said he will not provide details of how he committed the crimes.

“He said I wasn’t home during all of them,” Ellerup said.

When asked whether Heuermann admitted to killing any of the women in their shared home, Ellerup said he did.

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

Eleven sets of human remains — most of which belonged to those of sex workers — were found along Gilgo Beach between 2010 and 2011. A search for Shannan Gilbert, who disappeared in 2010, prompted the discovery of all of the remains.

Heuermann is not charged with Gilbert’s death.

He was arrested in 2023 in connection with the deaths of Melissa Barthelemy, 24, Megan Waterman, 22, and Amber Costello, 27. The women disappeared in 2009 and 2010, and were among the “Gilgo Four,” a group of sex workers whose bodies were found in the area in 2010.

In 2024, Heuermann was charged with killing Maureen Brainard-Barnes, 25, the fourth woman of the “Gilgo Four.”

He was later charged with killing three more women whose remains were found on the beach parkway: Jessica Taylor, 20, who disappeared in July 2003; Sandra Costilla, 28, whose remains were found in Southampton in 1993; and Valerie Mack, 24, who disappeared in 2000.

In court earlier this month, Heuermann admitted he was responsible for all of their deaths, and for that of Vergata’s.

Heuermann is expected to be sentenced to life in prison without parole, three consecutive life sentences, followed by four sentences of 25 years to life. His sentencing is set for June 17.

NBC News asked an attorney for Heuermann for comment but had not received a response at the time of publication.

Peacock is owned by NBCUniversal, the parent company of NBC News.