Casey Arntz, a high school classmate of Bryan Kohberger, the 28-year-old Ph.D. candidate in criminology accused of killing four university students in Idaho, says her former friend was an overweight teenager who was bullied until he shed around 100 lbs. his senior year of high school.

“It was after that weight loss that a lot of people noticed a huge switch in him,” Arntz told the television news magazine 48 Hours in a recent interview. She also claimed her brother was bullied by Kohberger and that he was “kind of creepy” when she saw him a few years after high school.

Did the alleged killer’s past inform his future?

“We do know that these are people who did not have happy childhoods, typically,” says Dr. Phil in reference to serial killers, mass killers and school shooters. “We also know that they tend to feel marginalized and that unresolved childhood trauma comes to a crisis point sometime in their adult life.”

Forensic expert Joseph Scott Morgan says that’s why he believes authorities should look harder at Kohberger’s past. “I think it would be wise for the authorities in Pennsylvania to look anywhere this guy has been domiciled – wherever he hung his hat.”

Kohberger, who has been charged with one count of felony burglary and four counts of first-degree murder in the stabbing deaths of Ethan Chapin, Xana Kernodle, Madison Mogen, and Kaylee Goncalves, has reportedly maintained his innocence.

The conclusion of this two-part Dr. Phil, “Idaho Murders Suspect: Childhood Details Revealed,” airs Friday. And later, Dr. Phil talks to Kerri Rawson, daughter of Dennis Rader, the infamous serial killer known as BTK. Rawson talks about the similarities she has observed between her father and Bryan Kohberger.

Check your local listing for airtimes.

Watch more from part one: Eerie Details About the Idaho Murders Suspect

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