New details have emerged regarding the investigation of a suspect arrested in the killing of four Idaho college students.

According to KYW-TV in Philadelphia, a team of FBI agents and local police had quietly set in motion Bryan Kohberger's arrest four days before it took place on Friday by monitoring the suspect's movements in the days preceding him being taken into custody.

Law enforcement officials described an exhaustive investigation in which they fielded 20,000 tips and conducted more than 300 interviews of potential witnesses, according to CNN.

Kohberger ended up on the radar of authorities through DNA analysis and his ownership of a vehicle investigators suspected was close to the scene of the mass stabbing.

At one point during the investigation, authorities concluded that Kohberger's DNA matched the genetic profile of the suspected killer.

Investigators compared a DNA sample obtained at the crime scene to a public database -- using genetic genealogy to eventually identify Kohberger, according to CNN.

Investigators began tracking Kohberger when he drove from the Pacific Northwest to his parents' home in Pennsylvania around Christmas, according to CNN.

"An FBI surveillance team tracked him for four days before his arrest while law enforcement worked with prosecutors to develop enough probable cause to obtain a warrant, the two law enforcement sources said," CNN reported.

The accused murderer lived minutes away from the off-campus Moscow, Idaho, residence where the victims were attacked in their sleep on Nov. 13.

Kohberger was apprehended in Pennsylvania's Monroe County, across the country from Idaho and Washington State University, where he is a Ph.D student.

A probable cause affidavit detailing the nature of the four first-degree murder charges against Kohberger remains sealed until the defendant is extradited to Latah County, Idaho.

In a news conference following his arrest, police expressed confidence that Kohberger had acted alone in the killings, which shocked an Idaho community unaccustomed to violent homicides.

Kohberger maintains his innocence and claims he'll be eventually exonerated, according to CNN.

Monroe County Chief Public Defender Jason LaBar has indicated that Kohberger intends to waive extradition to face the murder charges.

“Mr. Kohberger is eager to be exonerated of these charges and looks forward to resolving these matters as promptly as possible,” LaBar said, according to CNN.

The 28-year-old is slated for a Monroe County extradition hearing on Tuesday, according to KYW.

This article appeared originally on The Western Journal.