Last week police arrested 59-year-old Rex Heuermann in connection with a string of bodies which were found on a barrier island off Long Island a decade ago. At the time, we didn’t know anything about what had tipped off authorities to the possibility that Heuermann was their suspect. Since then Heuermann was charged with three murders and we’ve learned a lot more about the evidence in the case. It turns out police have been looking at him for a full year.

Court documents obtained by The Post Friday detailed how investigators first focused on Heuermann just last year, after a vehicle-registration search showed the local dad of two owned a first-generation model of the truck that had previously been tied to the then-unknown killer.

It is unclear why it took so long for authorities to apparently make the link between Heuermann and the car, given that the architect seemed to make no effort to hide it.

The Suffolk County District Attorney’s Office confirmed to The Post on Monday that the detail about a dark-green Avalanche being linked to the case came in soon after the bodies of the “Gilgo Four” were found strewn around Ocean Parkway in December 2010.

“That tip came in very early on in the investigation,” a rep with the DA’s office said.

Heuermann had the truck parked in front of his house just a 15 minute drive from the crime scene where the bodies were found. That seems like it maybe should have been followed up a lot earlier. They also had a vague description of the suspect though it’s not clear if this was given to police a decade ago or more recently. A witness described him as an “ogre.”

On Sept. 1, 2010, Costello got a call from a burner phone. A man seeking to buy sex entered her house. She executed a ruse: She took the money, and then a man posing as her boyfriend showed up, enraged. The client backed off, saying he was “just her friend.” A little later, around 1:18 a.m., she received a text from the burner phone: “That was not nice so do I [sic] credit for
next time.”

The same client contacted her the next night. Costello agreed to meet him. She left her house and left her cellphone. She was never seen alive again.

A witness described the man to police. He was a large, white male, about 6-foot-4 or 6-foot6, in his mid-40s, with dark, bushy hair and glasses, like an “ogre,” according to court papers.

When the bodies were originally found buried along the beach, they were too degraded for DNA testing that existed at the time. But testing has improved since then and eventually hairs found on the victims were connect to Heuermann’s wife.

A single female hair had been found on Brainard-Barnes and two each on Waterman and Costello. Investigators sent them to an outside lab, which determined in July 2022 that those hairs belonged to a woman who was not any of the victims, according to court papers.

On July 21, 2022, detectives retrieved 11 bottles from a garbage can outside Heuermann’s home. Further testing at a lab specializing in mitochondrial analysis linked the hairs to Heuermann’s wife. Yet she couldn’t have been near the women because travel records showed she was out of state when Barthelemy, Waterman and Costello disappeared, according to court papers.

The lab then examined a male hair found in the burlap around Waterman’s remains. After comparing the DNA on that strand of hair to the DNA on a discarded pizza crust that investigators pulled from the garbage on Jan. 26, they had a match: It belonged to Heuermann, according to court papers.

Apparently the investigation would have continued in secret for weeks or maybe months longer but recently investigators became concerned that Heuermann, who was still contacting prostitutes, might strike again. So they quickly moved to arrest him. Since then, they’ve turned up a bunch of new evidence including seven burner phones on which he called prostitutes and searched for information about the case:

Over the last year between March 2022 and June 2023, the suspected Gilgo Beach serial killer Rex Heuermann repeatedly looked online for updates in the investigation police say.

He searched for details about the victims and their families.

He googled the use of new phone technology in the case and looked for podcasts and documentaries about the murders.

And he even took a keen interest in the newly-launched task force – headed up by newly-appointed Suffolk County Police Commissioner Rodney Harrison – that was actively hunting for him…

He even searched Google for the answers to questions including “why could law enforcement not trace the calls made by the long island serial killer” and “why hasn’t the long island serial killer been caught”, court documents state.

Finally, this clip includes an interview with a woman who was in a professional group with Heurmann. She saved a phone message he left her. She says she remembers him once casually asking if she was familiar with the Gilgo Beach murders. At the time she thought it was just something the locals talked about but in retrospect she sees it very differently.