It seemed like a classic John Ray news conference last month, with the flamboyant Long Island lawyer stepping up to news cameras, bedecked in a polka dot tie and matching fedora.

For more than a decade, he had held such appearances like recurring sideshows, stepping up with a showman’s bravado to tout his latest lawsuit related to the Gilgo Beach serial-killing investigation or vent a new displeasure with investigators.

Now Mr. Ray had something new: the police at his side.

The Suffolk County police chief, Rodney Harrison, stood with him, nodding in support of Mr. Ray’s announcement that witnesses had made claims that would seem to connect more bodies to Rex Heuermann. Mr. Heuermann, a Long Island architect and suburban father, was arrested in July and charged with killing three of the 11 people whose remains were found at or near Gilgo Beach on the South Shore a dozen years ago.

As Mr. Ray detailed the claims, the Gilgo Beach Task Force, the team investigating the case, watched the broadcast and seethed. They had become used to Mr. Ray as a gadfly delivering barbs and brickbats with a flourish from his pewter-handled cane.

But now here he was trotting sensational claims on live television before their eyes. Having Mr. Harrison, a task force leader, by his side only sharpened the sting.

District Attorney Ray Tierney’s office immediately responded with a statement saying it had been blindsided by the announcement of new information in a case he was prosecuting after years of investigative dysfunction.

Because Mr. Ray and Mr. Harrison had not provided “ any advance notice” to the task force “investigating these murders day in and day out, we watched today’s press conference not knowing what was going to be reported,” Mr. Tierney said in the statement.

Mr. Tierney’s office will nevertheless speak with Mr. Ray’s witnesses, who have already been interviewed by Suffolk detectives and by Mr. Harrison himself, who said he has added two more detectives to field Mr. Ray’s leads and other tips.

Mr. Heuermann is charged with hiring three women as escorts, killing them and then wrapping their bodies in burlap, and is the prime suspect in the death of a fourth woman. Mr. Ray, who represents relatives of two of the victims and has filed a lawsuit on one family’s behalf, has become a consistent side player in the investigation as it has riveted the public over the past dozen years.

Now, his role has grown more central. Mr. Harrison said in an interview that one of the first things he did upon taking over the Suffolk police was to have lunch with Mr. Ray to discuss the Gilgo case.

“As much as people say he’s eccentric, or negative things about John Ray, the worst thing in the world as investigators is that someone credible comes to John Ray and we blow it off,” Mr. Harrison said. “One thing we’re not going to do in this department is ignore John Ray.”

At the news conference, Mr. Ray laid out claims that portrayed Mr. Heuermann as someone who threw sex parties with his wife present and terrorized women with shocking violence.

The claims come from women who Mr. Ray said have contacted him to describe terrifying encounters with Mr. Heuermann, including two that involved women later found dead: Shannan Gilbert, whose family Mr. Ray represents, and Karen Vergata.

One witness, Mr. Ray said, spoke of visiting Mr. Heuermann’s house in Massapequa Park for a sex party and seeing a terrified Ms. Vergata fleeing naked in the winter of 1996, around the time she went missing. Her skull was found near Gilgo Beach in April 2011.

Mr. Ray said another witness, a cabdriver, claimed to have picked up Ms. Gilbert fleeing Mr. Heuermann at a Suffolk County motel notorious for drugs and prostitution in late 2009, six months before she went missing.

Mr. Ray said the driver also claimed she was later threatened in her cab by a pistol-wielding Mr. Heuermann.

Mr. Tierney emphasized that Mr. Ray had no affiliation with the task force.

“Any attorneys representing victims or their families, by definition, have a conflict of interest and should not be a part of the investigation,” he said in the statement, adding that tipsters should report information to official investigative agencies.

Mr. Harrison, who announced his resignation for family reasons two weeks after the news conference, was widely lauded for reinvigorating the Gilgo task force upon taking office in early 2022. He and Mr. Tierney guided the task force, one that had bungled early leads, to major breaks culminating with the July 13 arrest of Mr. Heuermann, who has pleaded not guilty and is being held without bail at a Suffolk County jail while awaiting trial.

Mr. Harrison acknowledged that his appearance with Mr. Ray “caused a little friction” with the task force. “But I’m doing the investigating part, and if someone says there’s a connection to Rex Heuermann, that’s what investigators do.,” he said.

He said his departure had nothing to do with his appearance at the news conference.

A lawyer for Mr. Heuermann, whose next court conference is Wednesday, did not return requests for comment.

In 2011, Mr. Ray began representing the family of Ms. Gilbert, 24, whose disappearance sparked the search that led to the discovery of the Gilgo bodies.

As waves of investigators and elected officials cycled through, he has kept up his profile with countless media appearances. His office phone, he says, has become a tip line fielding several calls a day about the case, hundreds over the years.

“Most of them are not viable,” he said. “Some are crazy.” But when someone seems credible, he often meets with them and sometimes gets them to speak to the police.

Some people, especially women who have worked as escorts, have an aversion to speaking to the authorities, especially in a county where corruption engulfed law enforcement agencies in the investigation’s early years, he said.

“Why in the world would anyone expect to be treated fairly by a corrupt system? Many of them said, ‘I’m afraid to deal with the Suffolk County Police,’” said Mr. Ray, who has long challenged investigators’ finding that Ms. Gilbert probably drowned.

He once dressed in camouflage suit and hat and took a news crew into the marsh where Ms. Gilbert’s remains were found in December 2011 in Oak Beach, near Gilgo.

In 2016, he brought in his own medical examiner, who suggested Ms. Gilbert’s death was consistent with homicide.

And after years of legal pressure by Mr. Ray, the police in 2022 finally made public a frantic 911 call in which Ms. Gilbert claimed someone wanted to kill her.

Regarding criticism that he is a publicity seeker, Mr. Ray said his only interest is to see the cases solved.

“I don’t chase headlines,” he said. “They chase me.”

He said he has spent at least $50,000 to help the victims’ families uncover Gilgo-related evidence, and has devoted unpaid time — “I stopped counting at 30,000 hours” — for which “I haven’t made a dime.”

“All that for a little bit of fame — are you nuts?” said Mr. Ray, who drives Cadillacs and keeps an idiosyncratic office in Miller Place, N.Y., in a renovated 18th-century farmhouse with a sprawling koi pond.

At 75, he still plays lacrosse — goalie, no less — in several leagues against players a third his age. On his rambling website, he calls himself a “litigation war horse” whose motto is: “Audacity, more audacity, always audacity.”

He called Mr. Harrison’s openness by far the most cooperation he has gotten from Gilgo investigators.

After Mr. Heuermann’s arrest, Mr. Ray told Mr. Harrison about the uptick in tipsters calling him, including the cabdriver.

They met her in Manhattan. She told them about picking up the woman trying to escape a large man at a motel in 2009, Mr. Ray said, and described being called on a later date to a Suffolk County bar and picking up the same man, who then brandished a gun and threatened to kill her.

After the July arrest, she identified the man as Mr. Heuermann and the woman as Ms. Gilbert.

Mr. Harrison said he found the cabdriver witness “a person of substance” who called Mr. Ray after she “didn’t get the attention she thought she deserved” by calling the department’s hotline after Mr. Heuermann’s arrest.

Mr. Harrison said he had his detectives interview another woman who claimed to have visited Mr. Heuermann’s house in 1996 for the sex party along with her then-boyfriend, then a New York City narcotics detective, and Ms. Vergata, who was working as an escort.

The boyfriend seemed to know Mr. Heuermann and promptly left the room with him, leaving the witness to chat with Mr. Heuermann’s wife.

As she left, the witness said she saw Ms. Vergata, who had paired off earlier with Mr. Heuermann, darting outside naked and terrified, Mr. Ray said.

The boyfriend dismissed this as a “game” and neither reported it, Mr. Ray said, but the witness recalled it when Mr. Heuermann was arrested in July.

Mr. Harrison deemed the story worth exploring.

“The story was too detailed for me to say, ‘Someone actually made this story up,’” he said. “That doesn’t mean it’s credible, but it does make me want to look closer.”

In a phone interview, Mr. Tierney said the standard careful vetting of witnesses would certainly apply to those referred by Mr. Ray because as a private lawyer with a Gilgo-related lawsuit, he might have his own interest in the outcome of the case.

“I have my job to do, and he has his job to do and he does it in a very provocative way,” Mr. Tierney said. “He’s willing to turn information over to us which we appreciate. We’ll take it from anyone.”