Gilgo Beach murder suspect Rex Heuermann “staged” a car accident near his home years ago — then sued the elderly driver who struck him for $5 million, her angry boyfriend told The Post.

“It was a staged accident. He didn’t even get hurt,” insisted Steve VonDuerring, of Heuermann.

Heuermann, 59, who was arrested Thursday and charged with three of the Gilgo Beach murders and is considered a prime suspect in the killing of a fourth woman, sued VonDuerring’s girlfriend, Barbara O’Sullivan in 2017.

The Long Island architect claimed O’Sullivan left him seriously hurt when she struck him with her car on a rainy night in January 2017, as he walked home from the Massapequa Park train station.

He sought $5 million in the Nassau Supreme Court lawsuit he later filed against her, records show.

“She just tapped him. He didn’t fall down, and he sued,” said VonDuerring, who O’Sullivan called from the scene of the accident.

It was one of four such lawsuits Heuermann filed in state court between 2014 and 2022.

In each case, he claimed he’d been hit by a car and injured, and sought $5 million.

VonDuerring once accompanied O’Sullivan to a hearing in the case, and claims Heuermann “was making up lies — he couldn’t use his arm.

He said his arm was bad, his back was bad, he couldn’t go up and down a ladder.

“We saw him putting up his Christmas lights after that,” VonDuerring said.

They took pictures of Heuermann with his holiday lights and submitted them as part of the legal proceeding, according to court papers.

The case later settled, with the insurance company paying the architect $55,000, according to VonDuerring who added, “I don’t know why they gave him money.”

O’Sullivan declined to share the photos she had of Heuermann.

“I can’t. I’m under counsel. All I can say is he is weird. I have no comment,” she told The Post Saturday.

But in a deposition she provided in the case, O’Sullivan said she was driving just five miles per hour when Heuermann “walked right out in front of me” with his head down at the time of the accident.

When she asked Heuermann if he was ok, he told her, “I don’t know, I have to wait and see,” O’Sullivan said during the proceeding.

Heuermann claimed that he had to miss work due to the injuries sustained from the accident, according to his own deposition in the case.

A lawyer for Heuermann who represented him during the case did not immediately respond to a request for comment.

O’Sullivan was one of four people Heuermann sued for $5 million over claims that they hit him with their car between 2014 and 2022. 

Heuermann was arrested Thursday and charged in the deaths of Melissa Barthelemy, Megan Waterman and Amber Costello, whose bodies were among 11 sets of remains found on Gilgo Beach over the years.

He is the prime suspect in the death of a fourth victim, Maureen Brainard-Barnes, but has not been charged in her killing.

The married father of two, who has worked as an architect in Manhattan since 1987 and lives in Massapequa Park, pleaded not guilty Friday to first- and second-degree murder charges.

The case had laid dormant for years until Suffolk County Police, along with the Federal Bureau of Investigation, reinvigorated their probe.

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 Barthelemy, Waterman and Costello.