Idaho killing suspect Bryan Kohberger was arrested in connection with the four students' murders Friday.
Kohberger may have tracked the victims' phones before the killings, a source told the Daily Mail.
A local brewery owner told NBC that Kohberger was known to be "creepy" to female employees.
More details have emerged about possible links between the suspect in the murder of four Idaho college students and the victims.
Bryan Kohberger, 28, who is being held in a Pennsylvania jail, was arrested Friday on first-degree murder charges in the deaths of four University of Idaho students, and one count of burglary. Ethan Chapin, 20, Madison Mogen, 21, Xana Kernodle, 20, and Kaylee Goncalves, 21, were found dead in their home nearly two months ago by two other roommates, who police said likely slept through the killing.
The Washington State University criminal-justice graduate student, who lived just miles from the crime scene, was connected to the killings through DNA and his car, officials told CNN.
But some connected to Kohberger, a Pennsylvania native, claimed he has a history of lashing out at women, followed the victims before the killings, and was careful to avoid police after the murders, according to reports in The New York Post, the Daily Mail, and NBC this weekend.
A source told The Daily Mail that the suspect may have tracked the four victims' phones for weeks before the killing. Police have not confirmed the detail.
After the killings, Kohberger traveled back to Pennsylvania, where he was staying at his parents' home. A Pennsylvania police officer was among those who followed Kohberger leading up to the arrest, the source told the Mail, and observed that Kohberger wore gloves each time he went to the local supermarket in a possible attempt to avoid getting caught.
Jordan Serulneck, a Pennsylvania brewery owner, told NBC that Kohberger had acted "creepy" toward women in the past. Kohberger was a patron at Serulneck's Seven Sirens Brewing Company, in Bethlehem, not far from DeSales University, where Kohberger got a master's degree last year.
Kohberger was flagged as problematic at Seven Sirens after female employees and customers repeatedly complained that he was harassing them. He reportedly asked them where they lived and who they were there with, then would get angry when they did not respond, Serulneck told NBC.
Kohberger also once called one of the employees a bitch for not answering him, Serulneck said.
"From the outset, we had to understand this was an organized killer," she told the network.
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