NORTH PORT, Fla. >> Police in Florida today searched a vast wildlife reserve near the Gulf Coast for 23-year-old Brian Laundrie, a person of interest in the disappearance of his girlfriend, Gabrielle “Gabby” Petito.

More than 50 North Port police officers, FBI agents and members of other law enforcement agencies searched the 24,000-acre (9,712-hectare) Carlton Reserve in the Sarasota, Florida area. Authorities used drones, scent-sniffing dogs and all-terrain vehicles to search the reserve, which has more than 100 miles (161 kilometers) of trails, as well as camping grounds. Investigators took some of his clothing from his parents’ home Friday night to provide a scent for the search dogs.

“His family says they believe he entered the area earlier this week,” North Port Police tweeted Saturday.

Investigators were hopeful that Laundrie was somewhere in the wildlife reserve. Depending on his skills, he could survive out in the reserve for some time, said police spokesperson Josh Taylor at a midday news conference.

“Certainly, we prepare for all different possibilities, but you know, our goal is to locate him and bring him back to North Port,” Taylor said.

Laundrie’s family earlier told officers that they haven’t seen him since Tuesday. Police said the conversation Friday evening was the first time they’d spoken with the Laundries in detail about the case, and that the meeting came at the family’s request. An attorney for the family called FBI investigators and said they wanted to talk about Laundrie’s disappearance, police said.

Investigators were trying to verify the story told by Laundrie’s family members that they believe the reserve is where he went with only a backpack, Taylor said. One mystery is how Laundrie got to the reserve. Family members told investigators that he took his car, but the vehicle was found back at his family’s home, not at the reserve.

“We’re going by their word. We believe the vehicle made its way from here back to their house,” said Taylor. “Certainly, we’re looking at corroborating all the information that we’ve received.”

Earlier, the North Port Police said in a statement that they understood the community’s frustration over the lack of progress in finding the missing woman.

“We are frustrated too,” the statement said. “For six days, the North Port Police Department and the FBI have been pleading with the family to contact investigators regarding Brian’s fiance, Gabby Petito. Friday is the first time they have spoken to investigators in detail.”

Laundrie and Petito, 22, left in July on a cross-country trek in a converted van to visit national parks in the U.S. West. Police said Laundrie was alone when he drove the van back to his parents’ home in North Port, Florida, on Sept. 1. Petito’s family filed a missing persons report Sept. 11 with police in Suffolk County, New York.

Laundrie has been identified as a person of interest in the case.

“It is important to note that while Brian is a person of interest in Gabby’s disappearance, he is not wanted for a crime,” North Port police said in Friday’s statement. It added that the investigation is now a “multiple missing person” case.

An attorney for Brian Laundrie, Steven Bertolino, did not immediately respond to a request for comment from The Associated Press on Friday night.

Attorneys for the Petito family released a statement saying that Laundrie was not “missing.”

“All of Gabby’s family want the world to know that Brian is not missing, he is hiding. Gabby is missing,” the statement from the law office of Richard B. Stafford said.

Earlier in the week, Petito’s family pleaded for the Laundrie family to tell them where their son last saw her. Petito and Laundrie were childhood sweethearts who met while growing up on Long Island, New York. His parents later moved to North Port, about 35 miles (55 kilometers) south of Sarasota.

The couple’s trek in the Fort Transit van began in July from Long Island. They intended to reach Oregon by Halloween according to their social media accounts, but Petito vanished after her last known contact with family in late August from Grand Teton National Park in Wyoming, authorities said.

Police video released by the Moab Police Department in Utah showed that an officer pulled the van over on Aug. 12 after it was seen speeding and hitting a curb near the entrance to Arches National Park. The body cam video showed an emotional Petito, who sat inside a police cruiser while officers also questioned Laundrie.

Laundrie says on the video the couple got into a minor scuffle that began when he climbed into the van with dirty feet, and said he didn’t want to pursue a domestic violence charge against Petito, who officers decided was the aggressor.

Ultimately Moab police decided not file any charges and instead separated the couple for the night, with Laundrie checking into a motel and Petito remaining with the converted sleeper van.