On September 1, Laundrie returned in Petito's van to the couple's North Port, Florida, home from a cross-country road trip the couple embarked on earlier in the summer, police have said.

It is currently (waist) deep in water in many areas," North Port police said in a Facebook post last month.

"This is dangerous work for the search crews as they are wading through gator and snake infested swamps and flooded hiking and biking trails."

CNN asked survival experts if it's possible Laundrie is alive if he has been in the reserve since mid-September.

If Laundrie was in the reserve for this long, he would likely also not be operating under the best mindset, several experts added, due to the anxiety of trying to evade authorities and trying to survive, which could hinder his survival skills.

"When you're tired, you're not as defensive, you're not as vigilant as you should be," Urban said.

But North Port police spokesperson Josh Taylor told CNN's Randi Kaye on Friday authorities have not found any physical evidence of Laundrie in the reserve.

Taylor, the North Port police spokesperson, told CNN it is "certainly possible" that Laundrie is alive.

"Nothing to suggest one way or another," Taylor said in an email.

The survival experts CNN spoke to seem to agree that Laundrie is either no longer alive or not in the reserve.

"Some non-trained guy just used to walking on trails is not going to evade a team of experts like that, just by hiding," Urban said, adding that he also believes Laundrie is either not in the reserve or not alive in there.

If Laundrie is in the reserve but no longer alive, finding him becomes harder as more days go by, Urban added, with the movement of water and sand, as well as the animals that go by.