Gabby Petito's parents appear to have a strong case against Brian Laundrie's parents, Chris and Roberta.

In the journal found with Brian's remains, he made the astonishing accusation that he murdered his girlfriend.

He wrote in his notebook that he killed Gabby because she had an injury and refused to seek medical attention. Those following the case quickly questioned this allegation. 

Gabby Petito's remains were recovered in Grant Teton National Park in Wyoming after traveling on a cross-country journey with Brian on September 21, 2021, just days after she was reported missing.

However, the lawyer for Gabby's parents, Joe and Nichole, has made a statement denouncing Brian's family lawyer Steven Bertolino's publishing of the diary.

Pat Reilly claimed in a lawsuit against Chris and Roberta Laundrie that they failed to provide new facts concerning Gabby Petito's death.

"I find it hilarious that Mr. Bertolino believes he was, in complete honesty, publishing this," Pat told WFLA.

"Well, someone should ask him why he doesn't reveal the complete notebook - and, more crucially, why he doesn't release Roberta Laundrie's letter to her son," he said.

Pat stated in his statement that there is a copy of a letter that has "severe facts" concerning Gabby Petito's death.

READ ALSO: Brian Laundrie Letter Offers More Mystery Than Answers After THIS Was Revealed

"The 'burn after reading' letter is essential because it demonstrates the Laundrie family's [claimed] knowledge," says former US assistant attorney Neama Rahmani, who is now the president of West Coast Trial Lawyers, speaking to The Sun.

"This letter helps the Petito's establish what the Laundrie's knew and when they knew it, and while they were putting statements out about seeking for Gabby when they supposedly knew she was already dead," she added of the letter Roberto allegedly sent Brian.

"If the letter helps prove that Brian's parents knew he murdered Gabby, it's a very strong case," the legal expert continued.

Pat Reilly said that the letter, which was discovered at Chris and Roberta's house in Florida after being removed from Brian Laundrie's vehicle, is "undated" and was "written after" Gabby Petito was slain before the boyfriend committed suicide.

"I believe more will come out about the Laundries' behavior when discovery is undertaken, papers are subpoenaed, and individuals are deposed," Neama added.

Gabby's parents, Joseph Petito and Nichole Schmidt, are suing Chris and Roberta Laundrie for more than $30,000 in damages, claiming that Chris and Roberta Laundrie knew their son killed Gabby Petito.

The Laundries are not currently being investigated, but they swear they will fully comply with authorities once they are.

READ MORE: Johnny Depp Trial Mentioned At Brian Laundrie, Gabby Petito Hearing [DETAILS]