Crime Accused Idaho Killer Bryan Kohberger Repeatedly Messaged One of the Victims on Instagram: Source "He was persistent," an investigative source on the case tells PEOPLE By Steve Helling Steve Helling Steve Helling is a former senior staff writer at PEOPLE. He left PEOPLE in 2023. People Editorial Guidelines Published on January 17, 2023 01:40PM EST Two weeks before the slayings of four University of Idaho students last November, the man now accused of killing them sent a series of messages to one of the victims on Instagram, an investigator familiar with the case tells PEOPLE. In late October, an account that authorities believe belonged to Bryan Kohberger sent a greeting to one of the female victims, the source says. When he didn't get a reply, he sent several more messages to her. "He slid into one of the girls' DMs several times but she didn't respond," the source tells PEOPLE. "Basically, it was just him saying, 'Hey, how are you?' But he did it again and again." Madison Mogen, Kaylee Goncalves, Xana Kernodle and Ethan Chapin were all stabbed to death in an off-campus rental home in Moscow, Idaho, on Nov. 13. A masked intruder entered the home and killed the four students with a fixed-blade knife. Bryan Kohberger on Jan. 3, 2023. Matt Rourke/AP/Shutterstock More than a month later, authorities arrested Kohberger a 28-year-old graduate student and teaching assistant at Washington State University. He was charged with four counts of murder and one count of felony burglary. Kohberger was arrested at his parents' Pennsylvania home on December 30. He waived his extradition to Idaho, meaning he voluntarily agreed to return to the state to face the charges against him. He was transported back to Idaho on Jan. 4. Suspect Arrested in Killings of Four University of Idaho Students Ethan Chapin, Madison Mogen, Kaylee Goncalves and Xana Kernodle. Want to keep up with the latest crime coverage? Sign up for PEOPLE's free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases. According to the probable cause affidavit obtained by PEOPLE, one of the victims' surviving roommates said she saw the killer. The roommate described "a figure clad in black clothing and a mask," who walked past her as the person left the crime scene. The affidavit also alleged that Kohberger was linked to the crime scene from DNA and cell phone pings. Authorities remain tight-lipped about the alleged motive in the attack. They have not publicly discussed the relationship between Kohberger and the victims. Kohberger's now-deleted Instagram account — which was viewed by PEOPLE before it was removed — followed the accounts of Mogen, Gonclaves and Kernodle, but there was no public interaction. It's unclear why Kohberger didn't get a response to his messages, but authorities say that the victim may have missed them completely. "She may not have seen them, because they went into message requests," says the investigation source. (Instagram users are not notified when they receive a message from someone they do not follow back, and the messages go into a special folder.) "We're still trying to determine how aware the victims were of his existence." "There's no indication that he was getting frustrated with her lack of response," the source adds, "but he was definitely persistent." Kohberger has not yet entered a plea. His next hearing isn't until June 26. His attorney has not returned PEOPLE's messages for comment.