Rex Heuermann, the Gilgo Beach serial killer who pleaded guilty earlier this month to murdering eight women, confessed to his wife in a tense conversation that he killed seven of them in their family home.

In an excerpt of the finale of NBC Peacock’s ‘The Gilgo Beach Killer – House of Secrets’, Asa Ellerup discloses the haunting moment the mask slipped off her suburban husband, and she finally saw him as a murderer.

The excerpt does not state when the dramatic confrontation between Ellerup and her then-husband took place, or what triggered it, but she filed for divorce days after his arrest in July 2023.

‘He looked very nervous – very, very nervous,’ she told her lawyer in the clip from the upcoming episode, which will air in full on Thursday.

Throughout the face to face, she addressed Heuermann not as her husband of 27 years, but more formally, almost like a stranger.

‘I said to him, “So, Mr. Heuermann, I understand that you are confessing to me on these murders,”’ she says. ‘“Can you please tell me how many of these women did you kill?” He said eight.’

‘He said I wasn’t home during all of them,’ says Ellerup, who is in her early 60s and who, according to prosecutors, was always on holiday with their two children when the crimes occurred.

Her lawyer, Bob Macedonio, then asks her if any of the victims were murdered in their home in Massapequa Park, on Long Island. ‘He said yes, they were killed in his room downstairs, all except one,’ Ellerup says.

Rex Heuermann told his ex-wife Asa Ellerup that he had killed eight women in a face-to-face confession

Rex Heuermann, who was accused of the murders of eight women during a 17-year killing spree, pleds guilty at court in Riverhead, New York earlier this month

Ellerup said Heuermann admitted seven of the victims were killed in a the basement of their Long Island home, pictured

Asked if he hesitated when answering the questions, Ellerup said: ‘No – he just told me the answer.’

Heuermann’s admission was as calculated as the crimes themselves, as he calmly described how he waited until his wife was gone before turning their family home into a killing ground.

At one point, Ellerup said she had to mentally shut down to endure what she was hearing from the man she and their two adult children had shared a home with for so many years.

‘Well, I put a wall up,’ she explained.

Her attorney added that even the tone of the exchange reflected how far removed the moment was from their former life together.

‘She called him Mr. Heuermann,’ the lawyer said. ‘So his response was, “Oh, are we formal now? Mrs. Ellerup?”‘

But the tension quickly gave way to something more unsettling: a strange, almost familiar version of the man she once knew.

‘When he started talking, it started feeling like that’s the Rex I know,’ she explained. ‘But I didn’t want to see that one. I wanted to see the one I needed to see.’

Ellerup explained how Heuermann told her she ‘wasn’t home during all of them,’ indicating he acted while his family was away

Asa Ellerup, who divorced Heuermann after his arrest, has always insisted that she and her children had lived in complete ignorance of the crimes

Rex Heuermann, pictured alongside his ex-wife Asa Ellerup, admitted to killing eight women by strangulation

Ellerup had to somehow try to reconcile the fact the husband she had lived with for almost 30 years was also a wanted serial killer – and something he now freely admitted.

The quiet, clinical exchange is set to air in the final part of a documentary on Peacock detailing the life and crimes of the Gilgo Beach killer which prosecutors say terrorized Long Island for decades.

Only weeks ago, Heuermann brought a decades-long investigation to a dramatic close.

Inside a packed courtroom in Suffolk County, the 62-year-old architect pleaded guilty to multiple murder charges tied to the notorious Gilgo Beach killings – a case that had haunted Long Island for more than 30 years.

He admitted to murdering seven women between 1993 and 2010 – and acknowledged an eighth victim for which he had not been formally charged.

Speaking in a flat, almost detached tone, Heuermann confirmed he strangled his victims, many of whom were young women working as escorts.

Some were dismembered before their remains were scattered along remote stretches of coastline near Gilgo Beach.

The victims, including Melissa Barthelemy, Megan Waterman, Amber Costello and Maureen Brainard-Barnes, became known as the ‘Gilgo Four,’ their discovery in 2010 sparking a sprawling investigation that would drag on for more than a decade.

Additional victims, including Jessica Taylor, Valerie Mack, Sandra Costilla and Karen Vergata, were later linked to the same killer through DNA and forensic evidence.

The victims clockwise from left: Maureen Brainard-Barnes, Megan Waterman, Melissa Barthelemy, Amber Costello, Valerie Mack, Jessica Taylor and Sandra Costilla

Rex Heuermann also pleaded guilty to the murder of an eighth victim, Karen Vergata

The backyard of Rex Heuermann’s home in Massapequa Park during a search in June 2024

Heuermann is seen in selfies that were submitted as evidence in the case

Discarded pizza crust was seized for DNA testing. Such evidence later linked Heuermann to the Gilgo Beach case

For years, the case seemed unsolvable, bogged down by missteps, jurisdictional tensions and a lack of clear suspects.

But it all changed in 2023 when investigators quietly zeroed in on Heuermann using a combination of cellphone data, witness accounts and a crucial piece of DNA evidence retrieved from a discarded pizza crust.

The genetic material matched hairs found on victims, tying him to the killings.

Prosecutors said they deliberately kept the investigation secret to avoid tipping him off.

‘We wanted the one person who mattered, the murderer, to think it’s business as usual,’ Suffolk County District Attorney Ray Tierney said after the plea.

For decades, prosecutors say, Heuermann lived a double life – a suburban husband and father on the surface who was also a Manhattan-based architect who returned each night to a quiet suburban home in Massapequa Park.

But he was also a predator who used his family’s absence as cover to lure women into the house and kill them out of sight.

Asa Ellerup, the estranged wife of Heuermann, and their daughter Victoria, outside Suffolk County Court ahead of the court hearing on April 8

The family are seen together before Heuermann’s arrest on suspicion of being a serial killer

The family’s attorney said their lives had been ‘destroyed’ by Heuermann’s actions

Investigators search Heuermann’s home in July 2023, days after his arrest

That home, investigators believe, may have been the site of some of the most horrifying moments in the case.

Ellerup’s account appears to confirm what prosecutors long suspected: that at least some victims were brought inside the house, into a basement room, where they were killed while his family was away.

Prosecutors have said Ellerup and the couple’s children were out of town during the murders and had no knowledge of the crimes.

In court, Ellerup sat quietly as her former husband detailed his actions, at times gripping her seat, at others holding hands with her daughter.

After the hearing, she issued a brief statement expressing sympathy for the victims’ families and asking for privacy.

For those families, the guilty plea brought a measure of long-awaited closure.

Suffolk County Police conduct a search on December 14, 2010, along Gilgo Beach, where four bodies were found

A prosecutor has said he believes there are other bodies hidden off Ocean Parkway, the road running along Gilgo Beach

There are still questions over whether Heuermann was responsible for other bodies that were found near Gilgo Beach

Map shows the location of Heuermann’s home compared to Gilgo Beach where the remains of several victims were found

‘This has been a long journey of hope – hope that one day we would stand here and say her name with justice beside it,’ Melissa Cann, sister of victim Maureen Brainard-Barnes, said after the hearing.

Elizabeth Baczkiel, the mother of Jessica Taylor, said the plea lifted a burden carried for years. ‘I am glad that this is over as far as him pleading guilty,’ she said. ‘It took a big chunk of stress off of me and my family.’

Yet even with the confession, questions remain.

Investigators believe there may be additional victims. Others point to disturbing evidence recovered from Heuermann’s home, including what prosecutors described as a ‘planning document’ outlining how to select, kill and dispose of victims.