The criminology student accused of slaying four University of Idaho students had stalked his alleged victims before the November murders and wore gloves in a supermarket weeks afterwards, according to a new report.

Cellphone data shows that Bryan Kohberger, 28, was often in the same location as the three sorority sisters and one of their boyfriends before he allegedly slashed them to death as they apparently slept at an off campus house, a source close to one of the case’s investigators told The Daily Mail.

Kohberger also seemed to be careful about not leaving fingerprints in public even as he fled to his native state of Pennsylvania in recent days, the anonymous source told the outlet Sunday.

“He’s not stupid and has been very careful,” said the source, who claimed to be “good friends” with one of the cops who had surveilled the murder suspect in the days before his arrest.

“He followed him into a Giant [Pennsylvania grocery store chain] and wore gloves the entire time,” the source reportedly said of his investigator pal.

“Not sure if they ever interacted – but his cell phone pings followed their every move for weeks,” the source reportedly said of Kohberger’s alleged stalking.

Roommates Kaylee Goncalves, 21, Madison Mogen, 21, Xana Kernodle, 20, and Kernodle’s boyfriend Ethan Chapin, 20, were killed in the women’s apartment in the early morning hours of Nov. 13 after a night out in the college town of Moscow, Idaho.

Kohberger, who was arrested Friday in a pre-dawn raid at his parent’s house in a gated community in Albrightsville, Pa., had local ties to the Mail’s source, according to the report. The man’s sister and aunts and uncles live near the accused killer — who purportedly allegedly attended school with the source’s cousin.

“I’ve been so invested in this case the last 6 weeks, and to find out how close he is to us – and that one of our friends found him and arrested him is just crazy,” the source reportedly said.

Kohberger had continued to serve as a teacher’s assistant at the university before driving his white Hyundai Elantra across the country in the days before Christmas with suspicious cops hot on his trail.

His father — who is not said to be a suspect — had flown to Idaho to make the 2,500 mile drive with his son after Kohberger completed his first semester of the PhD program at the university, the suspect’s lawyer said.

Kohberger was on suicide watch at the Monroe County Correctional Facility, where he was being held without bail ahead of a Tuesday extradition hearing.

The suspect was “eager to be exonerated” and intended to waive his right to a hearing to expedite his return to Moscow to face four murder charges, Monroe County Chief Public Defender Jason LaBar told CNN.

The murder weapon in the case — a fixed blade knife — had not yet been recovered, according to investigators.

Kohberger, who was described as “super awkward” and “a little off” by students in the criminal justice and criminology department, did not change his routine or behavior in the weeks following the murders, Fox 13 Seattle reported.

Cops had honed in on DNA evidence and Kohberger’s car, which was seen near the site of the gruesome murders, to link the suspect to the crime, according to CNN.

The undisclosed forensic evidence was linked to the suspect after it was run through a public database, two law enforcement sources told the network Saturday.

The FBI then tracked the grad student for four days before making an arrest while it worked with local law enforcement to develop enough probable cause to obtain a warrant, the sources reportedly said.

Despite reportedly wearing gloves while shopping and adopting a business-as-usual routine in the classroom, Kohberger’s “arrogance” may have created a DNA trail that led police to the suspect, experts believed.

“If somebody like this was really a student of criminal justice and criminology, then he would understand certain things like Locard’s Exchange Principle,”  Prof. Joseph Giacalone, a retired NYPD detective sergeant who teaches at John Jay College of Criminal Justice, told The Daily Beast Saturday.

The principal he referred to is a forensic theory that states “every contact leaves a trace.”

“It shows you the arrogance of people like him, where he thinks he’s smarter than the cops because he read something in a book,” Giacalone reportedly said. “At the end of the day, experience trumps academics every day of the week and twice on Sunday.”

“It will be really interesting to find out, as we go, if he came prepared,” added the expert.

“Did he wear gloves, a Tyvek suit, what was he doing to not get caught? Was he covering his hair? Did he wear booties over his shoes, knowing that he’s going to be stepping in a lot of blood? Those are behavioral aspects, where [prosecutors] can say, ‘This was well thought-out and planned.”

The suspect’s educational track have led some to speculate if he was studying to be able to become a better violent criminal, which Giacalone reportedly said was possible but rare.

In the spring, Kohberger had reportedly asked for volunteers to speak about their “most recent criminal offense,” and “thoughts and feelings throughout [the] experience,” as part of his research.

At Pleasant Valley High School in Pennsylvania a decade ago — where the suspect had recently worked as a part-time security guard — Kohberger had been mocked by classmates for being socially inept and overweight, classmates told Fox News Digital.

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Here’s the latest coverage on the brutal killings of four college friends:

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“It was bad,” former classmate Sarah Healey told the outlet, explaining that some girls in her class would throw things at him.

“There was definitely something off about him, like we couldn’t tell exactly what it was. It was just weird. But Bryan was bullied a lot, and I never got a chance to say something to defend him, because he would always run away.”

The suspect then shed weight before his senior year and became an aggressive bully himself by the end of high school, a former friend said.

The once overweight teen had developed “very, very weird” eating habits, his one-time aunt told The Post Friday.

“It was above and beyond being vegan,” said the woman, who was once married into his family and wished to remain anonymous.

“His aunt and uncle had to buy new pots and pans because he would not eat from anything that had ever had meat cooked in them. He seemed very OCD [obsessive-compulsive disorder].”

Kohberger also had made “creepy comments” to female staff at a brewery near his hometown and once called a worker “a b—h” for rejecting his advances, the proprietor told NBC.

Family members of the victims told The Post Friday that his arrest had brought them a level a of comfort.

“Of course we’re relieved,” Cheryl Goncalves, Kaylee’s grandmother said.

“This is what we wanted … We wanted him caught and now we want justice.”