The alleged Gilgo Beach slayer was in tears after his arrest on three counts of murder and sobbed, “I did not do this,” his lawyer revealed Friday.

However, by the time of his arraignment Rex Heuermann was silent and betrayed no emotion in court as he was formally charged with murdering three women whose bodies were found on Long Island in 2010.

Heuermann is a family man who is married to his second wife Asa Ellerup, 59. Neighbors told The Post Friday they have two children, a daughter and a son.

But to police, he is “a demon who walks among us. A predator who ruins families,” said Suffolk County Police Chief Rodney Harrison.

When asked if the alleged killer was surprised when placed under arrest, Suffolk County District Attorney Raymond Tierney responded: “I would say he was.”

The towering, shaggy-haired architecture boss is accused of being the same “ogre”-like figure with “dark bushy hair” who was seen soliciting sex from one of the victims months before her disappearance years ago.

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Heuermann, who had been arrested at his office in New York City the previous day, wore a gray polo and tannish pants in court.

He appeared unfazed as prosecutors rattled off a laundry list of reasons why he should be remanded at the Arthur M. Cromarty Criminal Court Complex in Suffolk County, New York.

Among investigators’ evidence were cellphone records, analyses of burner phones, Google searches and Heuermann’s DNA from a half-eaten pizza linking him to the killings of Melissa Barthelemy, Megan Waterman and Amber Costello.

Heuermann only spoke in court to confirm his name at the beginning of the packed hearing.

He pleaded not guilty to the charges before Judge Richard Ambro cited the “extreme depravity” of the crimes in ordering him held without bail.

He is charged with both first- and second-degree murder in the case of each of the victims.

Prosecutors alleged he had a secret life of seeking prostitutes, searching for child pornography and an obsession with the women he’s accused of killing and their families.

He taunted those close to the murders and kept tabs on them despite living what looked like an otherwise normal life as a successful New York City-based architect.

And though he stayed under the radar for years, Heuermann actively sought sex through websites and dating applications, such as Tinder, and used burner phones and bogus email addresses to send selfies and connect with prostitutes and other prospects, officials said.

He “continued to patronize sex workers at all hours of the night,” Tierney said.

His defense attorney, Michael Brown, reserved the right to file a bail application, citing the time needed to gather evidence.

“In terms of speaking to my client, the only thing I can tell you that he did say as he was in tears was, ‘I didn’t do this,'” Brown told reporters after the hearing.

He added that the case was “extremely circumstantial in nature.”

A bail application released to the public shows Heuermann was charged in connection with only three of the eight women who have been associated with the Gilgo Beach serial killer, but notes he is the “prime suspect” in at least one more.

They claim Heuermann is also being eyed in the case of the death of Maureen Brainard-Barnes, whose body was found on the same beach years earlier.

The bodies of each of the three women Heuermann is charged with killing were found along the same stretch of Long Island’s Gilgo Beach between June and September 2010.

The case captured the nation’s attention as it was revealed the bodies of eight women had been found in the same general area in the past few years.

In January 2022, the police created a team of investigators specifically focused on the serial killer.

Although police have yet to say what initially put Heuermann in their sights, just two months later they learned he owned a first-generation Chevrolet Avalanche, which was described by witnesses as the vehicle driven by Costello’s killer.

The discovery led to more than 300 subpoenas and search warrants executed over the ensuing months. Investigators plucked through at least a dozen trash cans, both public and those from Heuermann’s private home, and watched him carry out his day-to-day life.

They struck gold on Jan. 26, 2023, when surveillance teams pulled Heuermann’s leftover pizza crust from a garbage can along Fifth Avenue in Manhattan, prosecutors said.

DNA plucked from the pizza linked Heuermann to a man’s hair found on a piece of burlap that was used to wrap Waterman’s body, the document states.

Other hair found with three of the victims was later found to have DNA belonging to Heuermann’s wife.

Investigators said Heuermann’s wife and children were out of town around the same time three of the women disappeared. In Waterman’s case, she was in Maryland, the application states.

She was in New Jersey when Costello vanished and Iceland when Barthelemy was last seen.

And he made extensive searches on the Gilgo murder and family members of offspring, including over 200 in a single four-month period, Tierney said.

One search allegedly asked: “Why hasn’t the long island serial killer been caught.”

Another stated: “Why could law enforcement not trace the calls made by the long island serial killer,” the document alleges.

Investigators also uncovered cellphone records linking him to “the burner cellphones used to arrange meetings with three of the four victims,” as well as to make “taunting calls to a relative of Ms. Barthelemy,” and a “call made by a detective to Ms. Barthelemy’s cellphone while looking into her disappearance” as well as “calls checking voicemail on Ms. Brainard-Barnes” cellphone after her disappearance.

Heuermann also used burner phones when contacting each victim, and trashed the device after their murder, investigators alleged.

Just months before her disappearance, he allegedly pretended to be Costello’s “friend” during a shakedown that cut their tryst short.

Heuermann later texted Costello from a burner phone, “That was not nice so do i [sic] credit for next time.”

Records show Heuermann was in his hometown of Massapequa Park within two minutes of sending the text.

Heuermann was also captured on surveillance footage paying for additional use of the typically untraceable device.

Who is Gilgo Beach serial killer suspect Rex Heuermann?

A suspected serial killer has been arrested over the notorious Gilgo Beach murders in Long Island, The Post can confirm.

Rex Heuermann, 59, a married dad of two and architect at a New York City firm, has a home on 1st Avenue in Massapequa Park, sources told The Post.

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His arrest is tied to the “Gilgo Four,” four women — Melissa Barthelemy, 24, Megan Waterman, 22, Amber Lynn Costello, 27, and Maureen Brainard-Barnes, 25 — found wrapped in burlap within days of each other in 2010. 

The body of Barthelemy was first found along Ocean Parkway on Dec. 11, 2010, sparking fears of a serial killer in the area.

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By spring 2011, the number of bodies had climbed to 10, including eight women as well as an unidentified man and toddler.

Heuermann’s arrest comes after Suffolk County’s new police commissioner created a special Gilgo Beach Homicide Investigation Task Force in February 2022.

Records further show Heuermann was also no stranger to burner email addresses, such as one subscribed to the alias Thomas Hawk.

The bogus email address was used “to conduct thousands of searches related to sex workers, sadistic, torture-related pornography and child pornography,” prosecutors said.

Tierney described the searches as, “a lot of torture porn. Depictions or women being abused, rape and even killed.”