"Brian, you know how much I love you. So (and I'm writing this with love) just please stop crying and stop calling me names because we're a team and I'm here with you," Petito wrote in the undated letter, included among 366 pages of records from the FBI's investigation of the case. "I'm always going to have your back."
"You in pain is killing me," Petito writes. "I'm not trying to be negative but I'm frustrated there's not more I can do."
While it's unclear when the letter was written, Petito references plans to work together on the van that they would later take on the trip, which ended late in the summer of 2021 with Petito's disappearance. She was found more than a week after her parents reported her missing, strangled in Wyoming's Bridger-Teton National Forest. The coroner determined she had been dead for three to four weeks before being found.
By that time, Laundrie - who returned to his parents' North Port, Florida, home without Petito - had vanished into a nature reserve, leading to a weekslong manhunt. His remains were eventually found alongside a number of his personal items, including a notebook in which the FBI said he admitted killing Petito. A medical examiner determined he died by suicide.
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Petito's letter to Laundrie makes up just two of the hundreds of pages included in the FBI documents published on a website where the agency shares records released in response to Freedom of Information Act requests.
A number of the documents are redacted, but they outline the FBI's efforts to trace the couple's movements around the time of Petito's disappearance reported on September 11, 2021, recounting interviews with witnesses and descriptions of surveillance footage captured at gas stations and stores across the US.
Also included are scores of photographs of items recovered by authorities after the execution of a search warrant on September 20, 2021, including Petito's letter to Laundrie. The address where the warrant was executed is redacted, but the records indicate they stemmed from an investigation in North Port.
Asked about the letter, Steven Bertolino, an attorney for Laundrie's parents, told CNN Tuesday that Petito and Laundrie "both had their moments and had their issues."
"This is a tragedy that I've said all along that has affected two families," he said, describing a "lopsidedness" that has taken a "toll" on his clients.
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"There are always two sides to every story but as of this moment, there has only been one side put out there and that's the side that everybody's running with," Bertolino said.
CNN has reached out to an attorney for Petito's parents for comment on the letter.
There is no context for Petito's letter, and it's unclear why the couple was at odds when she wrote it. But it appears to foreshadow strains in the relationship that would spill out into the open over the course of their trip, perhaps most notably in Moab, Utah, where police body camera footage captured the pair two weeks before Petito's death.
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The incident - now at the heart of a lawsuit by Petito's parents against the Moab Police Department - occurred after a witness "saw Brian hit Gabby," according to an amended complaint filed earlier this year.
The footage shows Moab police officers talking to Petito and Laundrie, who admitted having a fight in which Petito said she struck her fiancé first. The officers let the couple go after they agreed to spend the night apart.
The lawsuit claims the officers improperly concluded Petito was the "primary" aggressor despite injuries to her face, failing to recognize that Petito's attempt to take responsibility for the altercation was an "obvious" sign she was a victim of domestic abuse.
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"The purpose of this lawsuit is to honor Gabby's legacy by demanding accountability and working toward systemic changes to protect victims of domestic abuse and violence and prevent such tragedies in the future," James W. McConkie, an attorney for Petito's parents, said in a statement when the lawsuit was first filed.
The city of Moab has previously said its officers "acted with kindness, respect, and empathy" toward Petito, noting they "are not responsible" for her death.
"The attorneys for the Petito family seem to suggest that somehow our officers could see into the future based on this single interaction. In truth, on Aug. 12, no one could have predicted the tragedy that would occur weeks later and hundreds of miles away, and the City of Moab will ardently defend against this lawsuit," the city said.
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