Gabby Petito's parents filed a lawsuit in Florida on Friday, claiming her killer's parents knew more than they let on, and even alleged they planned to help their son get out of the country.

Joseph Petito and Nichole Schmidt, Gabby's parents, are seeking damages from Brian Laundrie's parents, arguing in their lawsuit that the couple knew Gabby was dead and failed to comply with law enforcement during her family's desperate search for answers.

"Brian Laundrie murdered Gabby Petito in Wyoming on August 27, 2021 while they were on a cross country trip," read a letter put out by attorney Richard Stafford's office, which represents Petito's family. "Gabby and Brian were engaged to be married and would have been part of the Laundrie family. This meant nothing to Christopher and Roberta Laundrie after their son ended Gabby’s life."

Among their claims, according to the lawsuit filed on the six-month anniversary of the day Gabby Petito was reported missing, her parents say Brian Laundrie told his parents that Gabby was dead the day after he killed her, Aug. 28. They also allege the Laundrie's contacted an attorney that day, and that there were "multiple conversations between Brian, his parents and their lawyer" before Laundrie left Wyoming on Aug. 30, days before the family had retained the lawyer.

In that same complaint, Petito and Schmidt claim that Brian Laundrie used Gabby's phone to text her mother in an effort to hide her death, and in at least one text message referred to Gabby's grandfather by his name, Stan, which she never did, according to her parents.

Brian Laundrie continued to use Gabby's phone for several more days, until at least Aug. 30, when Schmidt received a text from her daughter's phone explaining that cell reception in Yosemite Park was bad, the complaint says.

The lawsuit describes "a cordial relationship" between both sets of parents prior to the road trip and death of Gabby Petito. In their lawsuit requesting damages, her parents claim the Laundrie's refused to cooperate and were silent while Schmidt and Petito desperately searched for Gabby.

"Christopher and Roberta had multiple opportunities to disclose to Joe, Nichole or the authorities that Gabby was no longer alive and to direct them to her body. Instead, Christopher and Roberta Laundrie showed callous indifference to the suffering of Gabby’s family and compounded her family’s anguish, pain and suffering by their actions," the letter for Stafford's office continued.

According to the complaint, Roberta Laundrie blocked Nichole Schmidt's phone, as well as her Facebook account.

"While Joseph Petito and Nichole Schmidt were desperately searching for information concerning their daughter, Christopher Laundrie and Roberta Laundrie were keeping the whereabouts of Brian Laundrie secret, and it is believed were making arrangements for him to leave the country," the complaint reads.

The docs did not elaborate on what arrangements Laundrie's parents were allegedly making to help their son flee.

Petito and Schmidt's lawsuit claims that the "willfulness and maliciousness" of Laundrie's parents in the search for their daughter, led to the couple's "pain and suffering, mental anguish, inconvenience, loss of capacity for enjoyment of life experienced in the past and to be experienced in the future."

Steve Bertolino, the lawyer for Chris and Roberta Laundrie, issued the following statement to NBC New York:

"As I have maintained over the last several months, the Laundrie‘s have not publicly commented at my direction which is their right under the law. Assuming everything the Petitos allege in their lawsuit is true, which we deny, this lawsuit does not change the fact that the Laundries had no obligation to speak to Law Enforcement or any third-party including the Petito family. This fundamental legal principle renders the Petito’s claims to be baseless under the law."