Authorities are wading through 'gator- and snake-infested swamps' to search for Brian Laundrie in Florida's 25,000-acre Carlton Reserve

• Florida police said Tuesday they'll continue searching a large nature preserve for Brian Laundrie.
• Laundrie's parents reported him missing 6 days after his fiancée Gabby Petito was reported missing.
• Police called the 25,000-acre Carlton Reserve in Sarasota County "a vast and unforgiving location."

Florida police said Tuesday that authorities will continue searching a vast nature preserve for Gabby Petito's fiancée, Brian Laundrie, just a day after they said they had "exhausted all avenues" in scouring the grounds.

Members of several law enforcement agencies, including the FBI, will head back into the sprawling Carlton Reserve where Laundrie's parents have said the 23-year-old North Port, Florida, man went for a hike a week ago and never returned, police said.

"This time, moving in from the Venice side of the area, along with adjoining lands," North Port Police Department spokesman Josh Taylor said Tuesday, adding, "A weekend ground search and aerial search Monday of the 25,000-acre preserve has yet to yield any answers, but we must press on."

Taylor noted that the Carlton Reserve, located nearby the Laundrie family home, "is a vast and unforgiving location at times."

"It is currently waist deep in water in many areas," Taylor said. "This is dangerous work for the search crews as they are wading through gator and snake infested swamps and flooded hiking and biking trails."

Taylor added: "This is an FBI-led criminal investigation and North Port Police are assisting our federal partner in any way we can to bring this investigation to a close."

On Monday, the FBI raided the North Port home where Laundrie and Petito lived with Laundrie's parents after FBI investigators announced Sunday that a body believed to be Petito's was discovered at a campsite in Wyoming's Bridger-Teton National Forest.

The Teton County Coroner's Office will perform an autopsy on the human remains on Tuesday.

Petito's family reported her missing in New York on September 11, 10 days after Laundrie returned home from a cross-country road trip out West without Petito in their van.

Laundrie, who was named as a person of interest in Petito's disappearance, quickly retained a lawyer and refused to speak to authorities about the case.

His family reported him missing on Friday.