The FBI announced on Sunday that the remains discovered in a Wyoming national park is most likely that of Gabby Petito, a missing Long Island woman who went missing while on a cross-country vacation with her boyfriend.

Petito's father, Joseph Petito, posted a photo of his daughter with the message: "She touched the world" immediately after the news. The finding of Petito's suspected remains was described as "heartbreaking" by the attorney representing Laundrie and his parents, who have all refused to talk to authorities about her disappearance.

Authorities discovered a corpse at Bridger-Teton National Forest, where FBI, National Parks, and local law enforcement personnel have been searching for Gabby Petito since last week, according to Teton County Coroner Dr. Brent Blue. Petito, 22, was last seen in late August while on a cross-country vacation with her boyfriend, Brian Laundrie, who returned home without her on September 1.

Gabby Petito's boyfriend now missing after suspected remains found in Wyoming

Per NY Post, the Blue Point resident last talked with her family on August 25, and two days later, a couple of YouTubers discovered her white 2012 Ford Transit van near Grand Teton - but said it seemed to be abandoned. Nichole Schmidt, Petito's mother, reported her daughter missing to Suffolk County police on September 11, and Laundrie was recognized as a person of interest in the investigation a few days later.

Before disappearing last week, Laundrie hired a lawyer and refused to speak to authorities, sparking a major search of the 25,000-acre Carlton Reserve near his parents' home in North Port, Florida. The search for the missing 23-year-old continued on Sunday until it was called off soon before 6 p.m., with no trace of him.

According to his attorney, the fiancee of missing van life blogger Gabby Petito has also vanished. Laundrie has been missing for many days, and his family has not seen him since Tuesday, according to Florida police, The Independent reported.

Authorities said they were now conducting multiple missing person investigations into Laundrie and Petito, and that while he was a person of interest in his fiancee's disappearance, he was not wanted in connection with any crime, in a statement sharing a photo of Laundrie and requesting information about his whereabouts.

As the hunt for Gabby Petito and Brian Laundrie continues, online investigators have discovered a video of Laundrie reading a book about missing women, as per Newsweek via MSN. Laundrie is briefly seen reading Jeff VanderMeer's book Annihilation in a video titled "VAN LIFE | Beginning Our van Life Journey," which was posted on Petito's YouTube channel Normadic Statik in August 19.

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Missing Long Island woman's family claims boyfriend not missing but hiding

Four ladies walk into an empty location in the book. Three of the ladies die, while the fourth remains in the area permanently.

The hunt for Petito was extended to Grand Teton National Park in Wyoming on Saturday, according to the Denver Federal Bureau of Investigations. Petito, 22, is said to have vanished in August while on his way to the park with Laundrie. After he had to go to their shared North Port house alone on September 1, she was initially reported missing on September 11.

She was last seen on August 24 at the Fairfield Inn & Suites in Salt Lake City, according to reports. The pair was traveling from Utah's Arches National Park to Grand Teton National Park. She last spoke with her family over FaceTime on August 25.

Authorities are still looking for Laundrie in Florida, focusing their efforts on the huge Carlton Reserve, an alligator-infested region, since Petito's family claims he isn't missing but rather "hiding." He went missing on Friday, and authorities believe he might live for months in the swampland if he's still there.

The Moab City Police Department released body-cam footage earlier this week that showed Petito obviously agitated and Laundrie with scratches on his face following an argument between the two. She was overheard discussing her mental health with an officer, as well as how the altercation began after he locked her out of the van.

Related Article: Gabby Petito Still Missing: Police Look Into Link Between Disappearance and Double Murder Case in Utah; Boyfriend's Sister Speaks Out