Authorities say a body discovered Sunday in Wyoming is believed to be Gabrielle “Gabby” Petito.

The FBI said the body was found by law enforcement agents who had spent the past two days searching campgrounds on the east boundary of the park.

Petito and her boyfriend, Brian Laundrie, 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.

Laundrie has been identified as a person of interest in the case. He was last seen Tuesday by family members in Florida, and investigators have been searching for him for the past two days in a 24,000-acre wildlife reserve near Sarasota, Florida.

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 a statement. It added that the investigation is now a “multiple missing person” case.

Laundrie’s family members told investigators that the last time they saw him was on Tuesday when they believe he went to the wildlife reserve in the Sarasota area.

Petito’s family had been pleading 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 the end of October 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.

The FBI in Denver said Saturday that agents have begun conducting ground surveys at Grand Teton National Park, with help from the National Park Service and local law enforcement agencies, seeking clues to Petito’s disappearance.

FBI agents tweeted that they were focusing on an undeveloped camping area near Spread Creek on the east boundary of the park, which was closed to the public during the surveys. They urged anybody who had been there between Aug. 27 and 30, and had seen Petito, Laundrie or their vehicle, to contact them.