The suspect arrested in connection to the murders of four Idaho college students was nabbed at least in part thanks to "genealogical DNA" evidence, sources told Fox News' Judge Jeanine Pirro.

"[M]y sources are telling me that there is genealogical DNA that was established in this case that led the police to this particular suspect," Pirro said on "The Five" Friday.

"So although that was, according to my sources who are very credible and reliable, …. if you try murder cases and especially murder cases that involve several victims, you understand that really the investigation begins now."

Pirro recounted how Idaho authorities said during an afternoon press conference Friday that suspect Bryan Kohberger's probable cause affidavit will be unsealed after he is successfully extradited from Pennsylvania – where he was captured – to Idaho.

CRIMINOLOGY GRAD STUDENT HIT WITH FOUR COUNTS OF FIRST DEGREE MURDER: POLICE

Bryan Kohberger and the victims of the Idaho murders

Bryan Christopher Kohberger was arrested Friday morning in connection to the murders of four University of Idaho students. Officials released few details about killings or the suspect during a Friday news conference. (Washington State University/ Instagram)

Kohberger was arrested early Friday in a private community near the Pocono Mountains village of Jonas, Pa. He was arraigned before a Monroe County judge and remains in custody.

The suspect was a PhD student in criminal justice/criminology at Washington State University – not far from the University of Idaho – and had previously graduated from DeSales University in Allentown, according to the AP.

On "The Five," Pirro said investigators will likely look even deeper into Kohberger's background.

IDAHO MURDER SUSPECT: WHO IS BRYAN CHRISTOPHER KOHBERGER?

Kohbergers home behind police tape

Police executed a search warrant at a home near the Washington-Idaho border Friday, Dec. 30, 2022, just a few minutes from where four University of Idaho students were killed on Nov. 13. (Stephanie Pagones/Fox News Digital, Inset: Monroe County (Pa.) Correctional Facility)

"The issue is, what did he say? Who did he hang out with? When he was in school did he talk about doing this kind of thing as a criminal justice major? He was interested in what the criminal was thinking when a criminal committed a violent crime. So there are all kinds of additional evidence that will be gathered at this point going forward," she said.

"So when you try a murder case, you understand that you are still investigating until your closing statement. And I've done it many times now as it relates to genealogical evidence – they literally can get evidence back to the 1800s."

Pirro, who formerly served as a Republican district attorney in Westchester County, N.Y., said if Kohberger does not have a criminal record, he would not likely have gotten any hits in law enforcement's CODIS database, which would lead authorities to instead analyze blood from the crime scene for genealogy-related leads.

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"And so, they find out who were the relatives. Once they figure out who the suspect is, they then start to continue to investigate, spread out from Idaho to the car to Pennsylvania. And they populate with historical data," she said.

"So CODIS can give us that 30% solving of cases. But this genealogical DNA can give us a 90% chance of solving these cases. So in addition to what will be unequivocal evidence, they're going to have all kinds of circumstantial evidence in addition to that evidence, which we will see when the affidavit is unsealed."