Authorities said a body discovered in northern Wyoming was believed to be that of a 22-year-old woman who disappeared while on a cross-country trek. Her fiance is now the subject of an intense search in a Florida nature preserve.The FBI said the body of Gabrielle "Gabby" Petito was found Sunday by law enforcement agents who spent the weekend searching camp sites on the eastern border of Grand Teton National Park.The cause of death not yet been determined, said FBI supervisory Special Agent Charles Jones. Specifics on where and how the body was found were not disclosed.Full forensic identification has not been completed to confirm 100% that we found Gabby, but her family has been notified, Jones said. This is an incredibly difficult time for [Petitos] family and friends.Boyfriend Brian Laundrie, 23, has been identified as a person of interest in the case. He was last seen Tuesday by family members in Florida.SEE MORE: 22-Year-Old Never Returned From Road Trip With Her FiancJones and other law enforcement officials declined to take questions during a Sunday evening press conference in Grand Teton announcing the body's discovery.Petito's father, Joseph, posted on social media an image of a broken heart above a picture of his daughter with a message that said, She touched the world."An attorney who has been acting as a spokesman for Petitos family asked in a statement that the family be given room to grieve.Attorney Richard Benson Stafford indicated that the family would make a public statement at a later date, and he thanked officials with the FBI, Grand Teton Search and Rescue and other agencies that participated in the search for Petito.The family and I will be forever grateful, Stafford said in a statement.An undeveloped camping area on the east side of Grand Teton bordering national forest land will remain closed until further notice while the investigation continues, Jones said.Jones said investigators were still seeking information from anyone who may have seen Petito or Laundrie around camping sites in the area of Spread Creek, where law enforcement search efforts focused over the weekend.The pair left in July in a converted van to visit national parks in the U.S. West. Laundrie was alone when he drove the van back to his parents home in North Port, Florida, on Sept. 1, police said.More than 50 law enforcement officers on Sunday started a second day of searching for Laundrie at the more than 24,000-acre Carlton Reserve in Sarasota County, Florida, a wildlife area with more than 100 miles of trails, as well as campgrounds.Police in North Port, Florida said in a statement that they were heartbroken to learn of the discovery of the body and pledged to continuing searching for answers in the case.Petitos family filed a missing persons report Sept. 11 with police in Suffolk County, New York.Petitos 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 couples trek in the Ford Transit 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.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 bodycam video showed an emotional Petito, who sat inside a police cruiser while officers also questioned Laundrie.Moab police ultimately 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.Additional reporting by The Associated Press.