"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, he said that not all cases turn up links – because not every offender is a serial offender.
IDAHO MURDERS: HOW DOES CRIMINOLOGY STUDENT LEAVE CRIME SCENE WITH BLOOD-DRIPPING KNIFE?
Bryan Kohberger, left, who is accused of killing four University of Idaho students in November 2022, looks toward his attorney, public defender Anne Taylor, right, during a hearing in Latah County District Court, Thursday, Jan. 5, 2023, in Moscow, Idaho. (AP Photo/Ted S. Warren, Pool)
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," he added.
Referencing Kohberger's 2,500-mile cross-country road trip home with his dad a month after the slayings, he noted that there are also many unsolved cases that took place along interstate highways.
IDAHO MURDERS: BRYAN KOHBERGER'S TRASH MAY BE KEY IN MASSACRE PROBE
Kaylee Goncalves, one of the University of Idaho students killed on Nov. 13, dances with her dog Murphy (TikTok./ Kayleegoncalves0)
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.
IDAHO MURDERS: BTK SERIAL KILLER ON SOLITARY CONFINEMENT AND BRYAN KOHBERGER, ‘I KNOW HOW HE FEELS’
University of Idaho student and stabbing victim Xana Kernodle in an undated photo. (Instagram @xanakernodle)
Investigators in several neighboring counties have said they were looking into potential similarities in open cases.
Lehigh County District Attorney Jim Martin told the Seattle-based KING-TV that the first thing he did after learning of Kohberger's arrest was check a regional crime database. However, the only thing to come back was a 911 call Kohberger reportedly placed after leaving his car parked behind a gate that was later locked.
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.
UNIVERSITY OF IDAHO STUDENT STABBINGS TIMELINE
Senior pictures of Madison Mogen two days before she and three friends were killed in an ambush stabbing attack at her home in Moscow, Idaho. (Jessie Frost Photography)
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 this photo provided by Stacy Chapin, Ethan Chapin surfs on Priest Lake in northern Idaho in this family snapshot from July 2022. Chapin was one of four University of Idaho students found stabbed to death in a home near the Moscow, Idaho campus on Sunday, Nov. 13, 2022. (Stacy Chapin via AP)
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 that out as well.
Map showing a string of killings in the Washington-Idaho-Oregon region. Investigators ruled out a connection between the unsolved slayings and the Idaho stabbings, although the attacks shared similarities – including that some of the victims were attacked in their beds in the early morning hours. (Fox News Digital)
IDAHO INVESTIGATORS RULE OUT CONNECTION BETWEEN COLLEGE MURDERS AND OTHER UNSOLVED STABBINGS
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.
Bryan Kohberger, 28, is accused of killing Ethan Chapin, Xana Kernodle, Kaylee Goncalves and Madison Mogen. (Latah County Sheriff's Office)
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. He's being held without bail and is due back in court on June 26.
Judge Megan Marshall issued the initial gag order on Jan. 3, shortly after Kohberger's arrest, restricting comment from prosecutors, the defense, law enforcement and other officials.