Brian Laundrie claimed responsibility for the death of his fiancé, Gabrielle Petito, in a notebook before shooting and killing himself, the FBI said Friday.
No one else appeared to have been involved in the death of Petito, the agency said in what it called its final investigative update into Petito's disappearance and death, which sparked national headlines and a massive social media following after the 22-year-old went missing in September.
The couple had chronicled their cross-country road trips on social media and amassed a following of hundreds of thousands of their own, but questions arose when Laundrie returned to his home in North Port Florida on Sept. 1 without Petito. Laundrie was driving the white van the couple had driven in their "Van Life" YouTube channel, but Petito's whereabouts were unknown.
Gabby Petito's family reported her missing 10 days later. North Port police would later name Laundrie as a person of interest in the case, noting that he'd made no contact with authorities about Petito's disappearance and that he, and his attorney, had repeatedly refused to answer questions about her.
Investigators also believe Laundrie used Petito's cellphone multiple times after her death, sending text messages between her phone and his in order to try to deceive law enforcement and give the impression that she was still alive.
According to the FBI, investigators also believe Laundrie used Petito's debit card on his trip back from Wyoming to his family's home in Florida.
Laundrie's family then reported him missing on Sept. 17. Two days later, Petito's body would be found in Wyoming in the Grand Teton National Park.
Officials believe she died of "blunt-force injuries to the head and neck with manual strangulation."
An arrest warrant was issued for Laundrie on Sept. 22. About a month later, his body was found at the Myakkahatchee Creek Environmental Park. Near the body, officials also found a backpack with a revolver and a notebook that, according to the FBI, contained statements that he was responsible for Petito's death.
Officials did not release further details about the notebook's contents.
FBI officials said they did not expect to release any more information about the case.
"All logical investigative steps have been concluded in this case," Michael Schneider, FBI Denver Division special agent in charge, said in a statement. "The FBI's primary focus throughout the investigation was to bring justice to Gabby and her family."
The US National Suicide Prevention Lifeline is 1-800-273-8255. The Trevor Project, which provides help and suicide-prevention resources for LGBTQ youth, is 1-866-488-7386. Find other international suicide helplines at Befrienders Worldwide (befrienders.org).