Gilgo Beach suspect Rex Heuermann’s DNA to be ‘compared to other crimes’

The arrest of suspected Gilgo Beach killer Rex Heuermann could mean justice for an unknown number of additional victims thanks to a key piece of evidence: Heuermann’s DNA, NYPD sources told The Post Saturday.

The department plans to compare the accused serial killer’s genetic material — obtained from a discarded pizza crust, then matched to DNA found on the body of victim Megan Waterman — against its backlog of cold cases.

“His DNA was never in the system until they arrested him,” the source said. “Now we can compare it to other crimes.”

On Friday, Heuermann, 59, was charged in Suffolk County Criminal Court for the murders of Waterman, Melissa Barthelemy and Amber Costello, whose bodies were found wrapped in burlap along Ocean Parkway on Long Island’s South Shore in 2010. He is considered the primary suspect in the death of a fourth woman, Maureen Brainard-Barnes.

“If we have four, he probably did 10,” said Wendell Stradford, a former NYPD cold case detective. “As he got more comfortable with it, he probably figured out how to get rid of them.”

But the experienced sleuth, who was on the force for nearly 40 years, explained that matching effort won’t be as simple as it appears on television crime shows.

Investigators will have to identify similar cases, then make sure those victims’ DNA profiles have been added to the FBI’s CODIS (Combined DNA Index System) database before they can hunt for connections to the alleged killer, Stradford said. CODIS contains DNA profiles from federal, state, and local forensic laboratories.

“People are under the impression that we submit everything to CODIS,” Stradford said. “We do not because it’s very expensive, and you have to have a very good reason for doing it because the city is paying for it.”

That means cops may have to go back to their case files and laboriously submit old evidence to the database before any matches can be made, he added.

“The biggest thing in sex assaults are fingernail scrapings,” Stradford said — which medical examiners often won’t test in cases that lack a suspect.

“They’re like, ‘Do you have a suspect,’” he said. “If not . . . ‘We’ll keep them on file in the event that you get a suspect and then we’ll test.’ ”

Cops ‘not going to rest’

Meanwhile, Suffolk County Police Commissioner Rodney Harrison ripped Heuermann as “an animal” Saturday as he vowed to hunt down all the killers responsible for the murders of 10 victims – eight women, one man, and a toddler – whose bodies were found across Long Island in a string of grisly discoveries more than a decade ago.

“I’m not going to rest until we get all involved that committed all the crimes, whether it’s this animal — or someone else,” Harrison said in an exclusive interview with The Post.

Harrison, the NYPD’s former chief of department, has been hailed for revamping the Suffolk County Police Department and lighting a fire under the dormant Gilgo Beach investigation after 13 years of frustration.

“There’s some more work that needs to be done,” he said.

Meanwhile, video emerged Saturday of Heuermann’s arrest Thursday night.

The accused killer can be seen strolling obliviously down a Midtown Manhattan sidewalk, a messenger bag slung over his shoulder, according to footage obtained by WABC.

Suddenly, plainclothes officers can be seen stepping in front of and surrounding the architect, hustling him into custody.

The takedown occurred close to his Fifth Avenue office.

A few blocks away, at the Gardenia Deli at Eighth Ave. and 31st St., owner Hassan Alborat said Heuermann was a regular who was last in his shop about three weeks ago.

“It’s disgusting,” Alborat said of the accusations against the father of two. “He never talk a lot, just buy a sandwich, sometimes soda or water . . . Thank God they got him.”

Scouring family home

On Long Island, authorities pored over Heuermann’s ramshackle Massapequa Park home for a second day.

“We’re just going through his house looking to see if there’s any evidence. If he has any trophies,” a police source told The Post.

In the street outside, a throng of onlookers filmed investigators as they emerged with items that ranged from the mundane — a cat scratch pole, a framed picture, an empty bookcase — to the creepy: a child-sized collector’s doll with long blond braids and a colorful costume, entombed in an elaborate glass display cabinet.

Law enforcement officers clad in powder blue caps, white jumpsuits and blue rubber gloves dotted the property, sifting the space for further clues.

Former mayor Rudy Giuliani bizarrely turned up at the scene as well, grinning from the passenger seat of a dark SUV that drove along the suspect’s block, and asked an officer how close he could get to the alleged killer’s home.

Apparently unhappy with the response, the ex-prosecutor stayed in his car and drove off. He did not respond to a request for comment.

Heuermann appeared in court Friday afternoon and pleaded not guilty to three counts of first-degree murder and other charges related to the deaths of the three women over 10 years ago. The life-long suburbanite, who was emotionless in court, was also named the prime suspect in the fourth killing.

A lawyer for Heuermann did not immediately respond to a message seeking comment.

Additional reporting by Larry Celona and Khristina Narizhnaya.