The hulking serial murder suspect blamed for at least three bodies found in the marsh behind Long Island's Gilgo Beach allegedly lost it on a former police officer on the train just days before his arrest, then waited for him after their ride for a second confrontation, according to a new podcast.

The former officer, who asked not to be named, said his encounter with Rex Heuermann, a 59-year-old suspected serial killer, was "like a road rage without the car" on "The Ops Desk" podcast Monday.

Heuermann thought he owned the train, and anybody who disagreed was going to hear it from him – loudly – according to the former officer.

"It was my impression he felt it was almost his kind of right to be able to confront people and voice his opinion on whatever was going on around him — unsolicited," he said.

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The former officer said Heuermann began jawing at him on the train for some reason about two weeks ago, and he stood his ground, leading to a minor verbal altercation that he thought ended there. 

However, he said, after their train from Massapequa Park arrived at Penn Station in Manhattan, he found the 6-foot-4-inch suspected serial killer waiting for him at the top of the escalator – where he allegedly renewed the verbal assault. He did not go into specifics about what Heuermann said but claimed it was "off-color." 

"I kind of thought he was a bully and seemed to be the kind of person who felt he could get away with doing things because he was big, and people weren’t going to say anything," he said.

Additionally, he was getting away with things, allegedly, Paul Mauro, a retired NYPD inspector, a lawyer and the host of "The Ops Desk" podcast, noted.

The former officer said the encounter has nothing to do with the Gilgo case but said, "It would give you an insight into a mindset."

Mauro asked his interviewee how he knew he was dealing with Heuermann.

It was Heuermann's imposing size, paired with the release of his mugshot and audio on an interview from last year that featured the architect that went viral on YouTube Friday. It has since been taken down.

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"He’s actually missing his left front tooth, so that was pretty obvious," he said. "His voice is very distinctive, and when I saw the picture in the media today I immediately recognized him as the person I had this confrontation with two weeks ago."

The former officer said he decided to walk away because "discretion [is] the better part of valor."

"It was a bit odd," he concluded. "But listen, this is New York."

Suffolk County Police Commissioner Rodney Harrison described Heuermann as both a "demon" and an "ogre" who is accused of killing three young women, tying them up and dumping their bodies along a desolate highway 45 miles east of Manhattan.

He told Fox News Monday that a search of the suspect’s Massapequa Park home uncovered "an arsenal" of more than 200 firearms.

Police were also seen searching toolboxes on drone video taken from above his backyard, and they were also searching a storage facility in nearby Amityville Monday. 

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Police have been tracking him for months and finally nabbed him on Manhattan’s Fifth Avenue Thursday night, swarming him on the sidewalk around 8:39 p.m.

On Friday, Suffolk County District Attorney Ray Tierney announced a half-dozen charges against Heuermann, first- and second-degree murder each for three of the Gilgo victims – Melissa Barthelemy, 24, Megan Waterman, 22, and Amber Costello, 27.

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He remains the prime suspect in the death of a fourth victim, Maureen Brainard-Barnes, 25, and investigators have recovered another seven bodies in the surrounding area.

The murders remained unsolved more than a decade after the search for missing escort Shannan Gilbert, 24, first led police to the bodies of sex workers and other victims along Ocean Parkway, a largely unpopulated stretch of the waterfront east of New York City.