New theories on Brian Laundrie's whereabouts – is he dead or alive?

Weeks after police began a search for Brian Laundrie in a Florida reserve, a survival expert has weighed in and said the missing man is either dead, or not there.

Local and federal authorities have been searching for Brian Laundrie since mid-September, when he supposedly set off to the Carlton Reserve area in Florida.

The manhunt began after Brian’s partner, Gabby Petito was reported missing by her family, before her remains were found in Wyoming.

Gabby and Brian had embarked on a cross-country van tour together earlier in the year and he is now considered to be a person of interest.

Gabby Petito, who was last seen alive at Grand Teton National Park, is pictured with her boyfriend, Brian Laundrie.
Gabby Petito's remains were found after Brian Laundrie returned to Florida alone and he remains missing after weeks of searching. Source: EPA

The whereabouts of Brian remain a mystery, despite the widespread search, however, several survival experts have suggested why 23-year-old may be evading authorities.

There has been no evidence to suggest Brian is not alive, however founder and chief instructor of the Urban Survival Academy, Robert Urban, believes it is unlikely anyone with no professional training about survival in the wilderness would survive in the reserve for weeks on end.

“Some non-trained guy just used to walking on trails is not going to evade a team of experts like that, just by hiding,” Mr Urban told CNN.

He believes Brian is either not at the Carlton Reserve, or he is not alive, adding if he is dead, it will be harder to find him as the days go on, with the water, sand and animals in the area.

Mr Urban suggested Florida's climate would make for a difficult time in the reserve, but there are salso everal animals one might want to avoid at the reserve.

Gabby Petito's partner Brian Laundrie appears on police camera footage released by Moab Police Department.
Laundrie has been missing since mid-September. Source: The Moab Police Department via AP

'Living in hell' in the reserve

Alligators, black bears, rattlesnakes, coyotes and panthers are all found at Carlton Wildlife Reserve, the Sarasota Herald-Tribune reported.

“If he's down there in the Carlton Reserve, he's living in hell,” local survival expert Mark Burrow told the Herald-Tribune back in September.

Jason Marsteiner, founder and president of The Survival University told CNN while he has jungle training, he would not want to be out in the reserve for the time Brian supposedly has.

He said the trainees through his program, they go through a 50-day course before going into the wilderness for a week and even after the training, they struggle.

“He’s not sleeping well, and when you don’t sleep you slowly drive yourself insane," he said speaking of Brian.

"So he would be making bad decisions, bad choices and I think that would cause him to be found or get injured or perish.”

No one knows what Brian packed before he left for the reserve.

His parents initially told authorities he set out for a hike on September 14, then said their son actually left on September 13.

Authorities searching for Brian Laundrie leave Carlton Reserve in Venice, Florida.
The Carlton Reserve has been the focal point of the search for Brian Laundrie. Source: AP

It took Christopher and Roberta Laundrie days to tell authorities their son had not returned from the hike, telling them he set out for Carlton Reserve.

When he left, Brian only had a backpack, but experts say the best chance of him surviving this long in the reserve, would depend on how prepared he is.

He would need shelter, food and water and Dave Canterbury, a survival expert, told CNN he would need a way to disinfect water and process food if he was able to find any.

CNN reported there have been no physical evidence of Brian being at the reserve, but if he needed to process food and disinfect water, a fire would be an efficient way to do so.

Brian Laundrie likely somewhere 'comfortable'

Former FBI agent Bryanna Fox said it was unlikely Brian is still at the reserve, given there has been no trace of him for weeks.

Ms Fox suggested he had financial or transportation assistance, saying someone would call the police if they spotted him while hitchhiking or boarding a bus.

"The idea that nothing has been said reinforces to me that he was likely getting help," Fox told NBC News.

She added if he was getting help, it would have to be someone loyal and very close to him.

Adding weight to the theory Brian is not dead somewhere in the reserve was Alan McEwen, a cattle rancher who lives near the reserve.

He said if when something is dead in the reserve, buzzards would be flying around the area.

“You can’t see any buzzards flying anywhere, and no buzzards have been flying in any direction of this place,” he told CNN.

Search teams for Brian Laundrie fanout at Carlton Reserve near North Port, Florida.
Experts believe Brian Laundrie is either dead, or not at the reserve. Source: North Port Police Department via AP

The reserve has been closed since September 21 and Brian's father recently joined authorities in the search.

Former FBI agents Terry Turchie suggested Brian has gone to a place which is comfortable for him.

"People don't change because they become a fugitive," Turchie told Fox News,

"They tend to try to figure out how they can land in the comfort zone."

He added Brian is "clearly" not hiding out in a camp or cave, or somewhere he could be exposed to alligators or snakes.

"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.

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