As the notorious Gilgo Beach serial killer admitted to the torture and murders of eight women throughout Long Island, New York, this week, Rex Heuermann also made an unlikely decision that could help investigators gain insight into his nearly two decades of violence. 

Rex Heuermann has agreed to be evaluated by the FBI’s Behavioral Analysis Unit as part of a plea deal in which he received three life sentences without the possibility of parole for the brutal slayings of eight women in a case dating back to 1993. 

"They’re going to interview the defendant, gain insight into his motivations and background as sort of an academic and scientific exercise," Suffolk County District Attorney Ray Tierney told reporters after Heuermann entered his guilty plea Wednesday. 

"Those are clinical interviews," Tierney added. "Those aren’t investigative interviews. I believe that they’re going to limit that to just what he pled guilty to and just gain insight, so they can gain insight going forward and knowledge to move forward on new cases."

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Heuermann joins a list of infamous killers profiled by the "Mindhunter" unit, including Ted Bundy, Jeffrey Dahmer and John Wayne Gacy. 

The move could provide the FBI with priceless insight into the mind of one of the country’s most violent and calculated killers, according to Dr. Ann Wolbert Burgess, a pioneer of the Behavioral Science Unit. 

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"The advantage is what more can we learn about somebody who is very organized, very detailed and unfortunately very good at getting away with murder of many women," Burgess told Fox News Digital. "Even though he admits to eight [murders], he could have had more. We don't know – and that might be something that comes out of all of this."

The agency’s unit specializes in researching the psychological makeup of the criminal mind, with Burgess adding officials may have been interested in studying Heuermann due to specific aspects of his killings. 

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"At the time we worked on other cases [with the unit], they had to be serial so that you could find the pattern," Burgess said. 

"In this particular case, it has to be sexual homicide and I think as soon as these cases started lining up – even before they knew who did it – I am sure they were well aware and collecting data that was available."

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Under the agreement, Heuermann is obligated to be "truthful, accurate and complete" with the unit, defense attorney Michael Brown told reporters Wednesday. 

While Heuermann could hold the key to previously-unknown details surrounding the inner workings of a serial killer’s mind, Burgess cautions the ability to work alongside the FBI could feed into any narcissistic tendencies that are frequently observed in the most heinous criminals.

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"It keeps him in the spotlight, and he likes that," Burgess told Fox News Digital. "It’s really aligning him with a very elite group. So I think that feeds the ego – it’s certainly an ego thing." 

Heuermann’s decision to work with the FBI could potentially spark interest from another infamous killer – Bryan Kohberger, the man convicted of stabbing four University of Idaho students to death inside their home in November 2022.

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"I never knew whether they had made any kind of private agreement that he would answer some questions, because he really needs to," Burgess said. "Maybe that will loosen him up." 

The move also has the potential to bring closure to the families of Melissa Barthelemy, Megan Waterman, Amber Costello, Maureen Brainard-Barnes, Jessica Taylor, Sandra Costilla, Karen Vergata and Valerie Mack, according to Burgess.

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"We want to think of the victims’ families, because that’s who is left with many, many questions about what happened to their loved one," Burgess told Fox News Digital. 

"But at least we know now that the families have some closure in terms of what happened," she added. "So, in a sense, that is a plus for them."

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Ultimately, Heuermann’s work with the FBI could be pivotal in the prevention, investigation and prosecution of similar cases, with Burgess indicating the unit is likely planning a series of interviews with the now-convicted killer. 

"Each interview can go after different information," Burgess said. "Hopefully, they would want to do something on just how he planned it. Then they’d want to do something on any early red flags that could have alerted law enforcement – which would be very helpful for prevention. And third would be just how they do their investigation and prosecution."

Regardless of what information the Gilgo Beach serial killer hands over to the FBI, the key ultimately lies with Heuermann.

"I think this is a real win for them to get him to talk with the [unit]," Burgess said. "Now, it’s going to be important that the information is correct." 

Fox News Digital reached out to the FBI.