In a recent two-part "Dr. Phil" special, a panel of experts believed that the Idaho murder suspect may have left a "calling card" and "very likely" had killed before.

Kaylee Goncalves, Madison Mogen, Xana Kernodle, and her boyfriend, Ethan Chapin, were stabbed to death in Moscow, Idaho, in the early hours of November 13.

Ex-FBI: Bryan Kohberger Has Potentially Killed Women Before

Bryan Kohberger, a criminology doctoral student at the neighboring Washington State University, has been charged with four charges of first-degree murder and criminal burglary in connection with the quadruple homicide.

A knife sheath made of tan leather was discovered near the bodies of two killed by the University of Idaho students, but the murder weapon has not yet been retrieved, creating a wave of conjecture among the "Dr. Phil" panel of experts.

Former FBI agent Jonathan Gilliam said, "I think they'll find that knife. I think the knife could potentially be found because I think - like the car, and these things, I think these are part of his operational tools. It's no different than a go-bag for me."

When questioned, trial counsel Mercedes Colwin speculated that the sheath may have been purposefully placed at the crime scene. The panel also stated that this was maybe not Kohberger's first murder, making him a possible serial murderer. Gilliam offered his belief that the culprit may have previously committed a murder, Fox News reported.

Kohberger has been charged with four counts of first-degree murder for the November 13 deaths of college students Ethan Chapin, 20, Xana Kernodle, 20, Kaylee Goncalves, 21, and Madison Mogen, 21. In addition, he was charged with one count of burglary as a felony.

He was detained on December 30 in Pennsylvania while on Christmas vacation from Washington State University, where he is a doctoral student in criminology. Kohberger was extradited to Idaho on January 4, and he is currently being detained at the Latah County Jail.

Per The Washington Times, the defendant has not entered a plea. The preliminary hearing for the suspect has been postponed until June to provide Kohberger's defense team more time to analyze discoveries.

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Idaho Murders Suspect May be Driven by 'Incel Complex'

Meanwhile, a retired FBI agent told The NY Post that University of Idaho murder suspect Bryan Kohberger may have been motivated to kill by his history of social troubles and a suspected "incel complex." Pete Yachmetz, a former FBI agent and security specialist, indicated to The Post this week that the murders may have been an attempt to demonstrate some sort of control.

Occasionally, the identity is linked to misogynistic online forums and, in extreme situations, to criminal activity: In 2021, self-proclaimed incels will no longer exist. Tres Genco was arrested for plotting a mass killing at an undisclosed Ohio institution involving 3,000 sorority sisters. Genco pleaded guilty to the heinous conspiracy and now faces life in jail.

Although this is not a valid psychiatric description, Psychology Today reported last year that males who identify as incels frequently suffer from poor mental health and emotions of victimization, inferiority, and loneliness.

Yachmetz's appraisal of Kohberger mirrored that of forensic psychiatrist Dr. Carole Lieberman, who told CourtTV last week that she felt the suspect fit the incel description. Lieberman was also interested in evidence indicating Kohberger had returned to the crime site in the hours after the deaths.

Peers from Kohberger's Pennsylvania residence recalled him as a loner who was harassed for his weight before sliding into drug addiction, yet classmates at WSU characterized him as "gregarious."

Kim Kenley, a rumored middle school love of Kohberger's, contacted the FBI about her experience with him. As detectives attempt to establish a connection between Kohberger and the four victims, they develop hypotheses on his suspected purpose.

The suspect remains in detention in Latah County, where he is being detained without bond, following a brief hearing on Thursday. Kohberger is scheduled to return to court on June 26. He has not yet entered a plea to four charges of murder and one count of criminal burglary.

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