It's been 29 days since anyone has seen Brian Laundrie – including his parents.
Now, after the horrific circumstances surrounding the death of his fiancee Gabby Petito were revealed, a survival expert has weighed in on the various ways he could be remaining at large.
While Laundrie is only a person of interest in the case of the 22-year-old's death, which is being treated as a homicide, he is being sought by the FBI on credit card fraud charges for using her credit card.
Petito's body was found in Wyoming on September 19, with coroner Dr Brent Blue ruling as a homicide just days later.
Laundrie's whereabouts have been unknown for weeks, prompting a massive land, water and air search around Carlton Reserve near North Port, Florida. His parents, Roberta and Chris, claim their son went for a hike in the reserve on either September 13 or September 14 but failed to return home, forcing the pair to report him missing to local police on September 17.
But experts say he likely couldn't survive such tough conditions for so long – especially given he was only carrying a backpack.
In an interview with Insider, Jason Marsteiner, the founder and lead instructor of Colorado Mountain Man Survival, said if Laundrie is alive, it's only a matter of time before he makes "poor decisions".
"Especially if they don't have food; you're not eating what your body needs," he said. "You're either going to get angry or you are going to have some sort of emotional distress that makes you make poor decisions. Plus, he's got this stress of the situation – why he's being pursued to begin with.
"For somebody to go out in the woods, or wherever it is they are – for them to survive for 29 days now, for Laundrie, with a minimal amount of gear, it's going to be quite difficult. Surviving is not something that you're going to pick up quickly."
Robert Urban, the founder and chief instructor of the Urban Survival Academy in Florida, agreed, adding that a large part of surviving in the wilderness involved a person's mental strength and the "hope" they will be found, not the other way around.
"Survival is based on the hope that I'm going to get rescued," Urban said.
"When I do, my life's going to be better, and I'll be back with my friends and family and get back to normal. So there's a big positive mental attitude, even for experienced guys like myself.
"And the only way that you really have that mental fortitude is if there's that hope of it. So in this specific scenario of if this guy gets rescued – 'rescued' – his life is not going to be better than it was in the past," he added, alluding to the legal hurdles Laundrie could face if he's found.
With search efforts concentrating on the Florida wilderness, Laundrie would have faced a number of life-threatening circumstances by now including hot temperatures, dangerous animals like bears, snakes and coyotes, as well as poisonous food or dangerous bacteria in waterways.
In terms of cooking food for survival, Marsteiner said it takes great skill for smoke and fire to go undetected.
Another theory that's been floating around for weeks is that the 23-year-old is, in fact, dead.
But the fact police dogs and the scale of the search is so large, it would be surprising if his remains went undetected – though not impossible.
"You have so many animals that are hungry," Urban said. "You can be in a snake stomach, you can be in a gator stomach, or you can be eviscerated by a bear.
"An animal is not going to eat out in public. It's going to take [you] back to where it feels safe and sheltered," he said, adding that a "pack of hungry animals" could consume a body and leave behind little evidence.
North Port police, who are assisting the FBI with the search, said there is a "possibility" that Mr Laundrie has "hurt himself".
"As far as hurting himself in there, we don't know that one way or another. I think it's a possibility, certainly," North Port Police spokesman Josh Taylor told the New York Post.
Teton County coroner Dr Brent Blue today announced Petito's cause of death as strangulation, and confirmed the manner was homicide.
"After a detailed investigation by our forensic pathologists, our anthropologists and local law enforcements, the Teton County Coroner's Office filed the following verdict in the death of Gabrielle Petito," Dr Blue said.
"We hereby find the cause and manner of death to be … the cause death by strangulation, and the manner is homicide."
Dr Blue said no other information about the autopsy will be released, however they are estimating Petito died three to four weeks before the body was found in an outdoor environment.