Investigators who tracked down Idaho murder suspect Bryan Kohberger said that he stalked his targets for months before he allegedly killed 4 innocent college students.

According to court documents obtained by TMZ, between June 2022 and the date of the killings, November 13, 2022, Kohberger’s cell phone pinged in the area around the murder house at least twelve times.

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Authorities revealed on Friday that Kohberger, 28, was arrested in Pennsylvania and charged with four counts of murder and one count of felony burglary in connection with the stabbing deaths of Madison Mogen, 21, Kaylee Goncalves, 21, Xana Kernodle, 20, and Ethan Chapin, 20. The police had initially been mum about the investigation.

Kohberger waived extradition on January 3, and on January 4 he was moved to Idaho. On January 12, he will have his preliminary hearing and enter a plea to the charges brought against him. The probable cause affidavit has been made public now that Kohberger is back in Idaho, illuminating the circumstances that resulted in his arrest.

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The sheath of the knife used in the stabbings was allegedly left at the site in the bed where Mogen and Goncalves were discovered dead, according to the affidavit. Per the affidavit, this is where detectives discovered DNA linked Kohberger. According to the documents, agents allegedly retrieved trash from Kohberger’s parents’ Pennsylvania house to test for a DNA match.

Documents show that one of the roommates told authorities she overheard victim Kaylee Goncalves, who lived on the level above, remark “there’s someone here,” at around 4 AM the morning of the murders. This is one of the grisliest facts from the killings.

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The roommate claims she went outside but saw no one, but when she opened her door, she heard what she believed to be crying coming from victim Xana Kernodle’s room. Then, she claims she heard a male voice say, “I’m going to help you,” or something to that effect.

Kohberger was a Ph.D. candidate in criminal justice and criminology at Washington State University at the time of the killings. Eight miles separate the university in Pullman, Washington, from the Moscow, Idaho, home where the four students were killed.

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On the day the suspect was apprehended, a white Hyundai Elantra—the identical car police were looking for in connection with the case—was seized from the Kohberger family home.

In a statement on Friday, Moscow Mayor Arthur D. Bettge thanked law enforcement for their work on the case.

“I understand that law enforcement’s inability to share information during the course of the investigation has been frustrating, but their primary duty was to protect the integrity of the investigation and find a resolution to the case for the victims and their families,” the statement reads, in part. “I hope this arrest and subsequent criminal justice system process will begin to provide comfort and closure to the victim’s families, our community, and the nation.”