MOSCOW, Idaho - Idaho murders suspect Bryan Kohberger had a squeaky clean record — despite a past drug problem — and maintained a disciplined diet and fitness routine as he pursued advanced degrees in criminal justice and criminology.
But his arrest in a quadruple stabbing near the University of Idaho has piqued the interest for cold case investigators around the country and in his home state of Pennsylvania.
"One thing about cold cases is you always look to see if your case is connected to any others, and the reason behind that is many times those cases will hold clues for each one," said Joseph Giacalone, a former NYPD sergeant who was the commanding officer of the Bronx Cold Case Squad from 2007 to 2009. "If you can put them all together, you can put together the entire package."
Now a professor at John Jay College of Criminal Justice, Giacalone said that not all cases turn up links — because not every offender is a serial offender.
But if they are, investigators can spot patterns across different crimes in areas with ties to the suspect, he said.
"Any time you have a suspect where you believe there could be companion cases, you look at every place they lived, every place they worked," Giacalone added.
Referencing Kohberger's 2,500-mile cross-country road trip home with his father a month after the slayings, Giacalone noted that there are also many unsolved cases that took place along interstate highways.
Kohberger, who is from the Poconos region of Pennsylvania, had a master's degree in criminal justice from DeSales University in Lehigh County and was attending Washington State University in pursuit of a Ph.D. at the time of the slayings.
He is accused of sneaking into a home just off the nearby University of Idaho campus and killing four young people — 21-year-olds Kaylee Goncalves and Madison Mogen, along with their housemate Xana Kernodle and her visiting boyfriend Ethan Chapin, both 20.
All four suffered fatal knife wounds in a 4 a.m. ambush attack, according to investigators, who said they recovered a USMC-stamped Ka-Bar knife sheath near Mogen's body that had Kohberger's DNA on it. A surviving eyewitness also told investigators she saw a masked man wearing all-black clothing with "bushy eyebrows" leaving out an unlocked sliding door.
Investigators in several neighboring counties have said they were looking into potential similarities in open cases.
"As part of the office’s Regional Intelligence and Investigation Center, a search of Mr. Kohberger’s name just turned up one police report that states he was on a walking trail and the parking lot area closed at 5 p.m.," Jim Martin's office told Fox News Digital Wednesday. Martin is the Lehigh County District Attorney. "Mr. Kohberger called police to assist him in getting the gate unlocked to remove his vehicle."
Pamela Lehman, a spokeswoman for the district attorney's office, said investigators there do not believe that any other cases in the county are connected to Kohberger after looking into the database.
Northampton County District Attorney Terence Houck also told the station his office had looked for possible connections.
"Nothing with respect to Kohberger has come about in our investigations of cold cases or unsolved cases to this point, but we always continue to investigate and pursue leads," he told the station.
With the FBI involved, investigators will also have access to the federal Violent Criminal Apprehension Program, or ViCap, Giacalone said.
"We kind of understand what happened in Idaho, to a degree of course, so they’ll look for patterns," he said. "They have the FBI on board on this case already, so they have ViCap, which is designed to do just that, identify cases based on similarities, based on MO, based on signature, and a variety of things. They put it in a database, and it becomes searchable."
In Idaho, reports of a skinned dog across town from the quadruple stabbing shocked the public — but police quickly ruled out a connection.
And a trio of unsolved bedtime stabbings in the region also prompted investigators to look into possible connections, but authorities in the Pacific Northwest eventually ruled those out as well.
Kohberger had a troubled past, according to acquaintances who spoke with Fox News Digital, including a prior heroin addiction, but he does not appear to have a significant criminal history, aside from a few traffic stops.
Court records in his home county show only one case — his recent arrest and extradition in the Idaho student slayings. In Philadelphia, the district attorney's office said it has no prior cases involving Kohberger, and police said they were not aware of any connected cases.
Fox News Digital has reached out to a number of investigators in other jurisdictions throughout the region for more information.
Kohberger faces four counts of first-degree murder and a felony burglary charge.
He could face the death penalty if convicted. Kohberger is being held without bail and is due back in court June 26.
Judge Megan Marshall issued an initial gag order on Jan. 3, shortly after Kohberger's arrest, restricting comment from prosecutors, the defense, law enforcement and other officials.