Former FBI agent Terry Turchie says fugitives like Brian Laundrie "tend to try to figure out" how they can reach their "comfort zone" while on the run and are often located in those places.

Laundrie, 23, is wanted on debit card fraud charges and is a person of interest in the homicide of his 22-year-old fiancée, Gabby Petito, who was reported missing on Sept. 11. Laundrie's family last saw him on Sept. 13.

"People don't change because they become a fugitive," Turchie, who spent a year in the North Carolina mountains between 1998 and 1999 leading the hunt for Olympic bomber Eric Robert Rudolph, told Fox News Digital. "They tend to try to figure out how they can land in the comfort zone."

Brian Laundrie (Instagram)

Brian Laundrie (Instagram)

Laundrie enjoyed hiking and traveling, so some experts have suggested he may be in the wilderness or on the road, and several potential sightings have added some credibility to those theories. Others have suggested the fugitive may be closer to home and could be getting help from another person.

Laundrie's sister Cassandra described her brother in an interview as a "mediocre" survivalist.

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"Clearly he's not out in some camp or some cave somewhere on the hard, cold ground or … snake, gator-infested water. He's somewhere where he's probably being taken care of," Turchie said. "When you see how he came running home after something obviously happened, that kind of tells you what he's probably doing now.

Laundrie and Petito were traveling cross-country in a van when Petito disappeared. Laundrie returned to their North Port, Florida home, without Petito on Sept. 1. Ten days later, Petito's parents reported her missing. Laundrie's parents reported him missing on Sept. 17 but recently said the last time they saw him was on Sept. 13.

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Brian Laundrie (Moab Police Department)

Brian Laundrie (Moab Police Department)

The FBI found Petito's remains in Moose, Wyoming, where the pair was visiting Grand Teton National Park, on Sept. 19.

Turchie explained how a key player in the FBI's search for Rudolph in the 1990s was a man who shared some of Rudolph's interests. Rudolph had spent time talking to the man in his health food store in North Carolina, and the man ultimately gave the FBI helpful information about Rudolph after initially refusing to talk to the agency because he was staunchly anti-government.

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Laundrie may similarly be around people he knows or trusts. Driving to far-off places is "exactly the kind of thing that that may very well be what he's doing," but he would have to have finances in order to do so, Turchie said. One minor traffic error, too, could make "his fugitive run pretty short."

While all fugitives are different, they all "tire eventually, and many of them ended up being on the run for …. well over a decade," Turchie said, adding that he does not think Laundrie will be on the run for that long.

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"But the formula is essentially the same," the former FBI agent said of the search process. "You interview as many people who need this person as you can, you continue following that. You talk to neighbors, friends and you look for anything [the fugitive] might have said during a time that he didn't have this guard up where he hadn't done anything."

Those clues, Turchie believes, will ultimately lead officials to discover Laundrie in the same way it has helped them discover other fugitives.