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Gabby Petito’s parents have filed a civil lawsuit in Florida alleging that Brian Laundrie’s parents, Chris and Roberta Laundrie, were aware that their son killed their daughter and attempted to help him flee justice.

"Christopher Laundrie and Roberta Laundrie exhibited extreme and outrageous conduct which constitutes behavior, under the circumstances, which goes beyond all possible bounds of decency and is regarded as shocking, atrocious, and utterly intolerable in a civilized community," the lawsuit alleges. "As a direct and proximate result of the willfulness and maliciousness of Christopher Laundrie and Roberta Laundrie, Joseph Petito and Nichole Schmidt had been caused to suffer pain and suffering, mental anguish, inconvenience, loss of capacity for enjoyment of life experienced in the past and to be experienced in the future."

In early July, Petito, 22, and Laundrie, 23, left New York on a cross-country road trip in Petito’s white Ford Transit van. They made it as far as Jackson Wyoming by late August. By Sept. 1, Laundrie pulled into his parents’ driveway in North Port, Florida, driving her van with Petito nowhere to be found.

"It is believed that on August 27, 2021, Brian Laundrie murdered Gabrielle Petito," the civil complaint reads.

FILE - Gabby Petito in an undated photograph.

FILE - Gabby Petito in an undated photograph. (North Port Police)

BRIAN LAUNDRIE NOTEBOOK: GABBY PETITO'S KILLER CONFESSED IN WRITING BEFORE SUICIDE, FBI SAYS

Laundrie then sent phony text messages between his cell and Petito’s "in an effort to hide the fact" that she was dead, according to court documents and the FBI.

The complaint alleges that Laundrie confessed to his parents on Aug. 28 and that the Laundries hired lawyer Steve Bertolino, a longtime friend, on Sept. 2.

Bertolino told Fox News Digital Friday he has represented the Laundrie family "for many years" and called the civil lawsuit "baseless."

Brian Laundrie as seen in bodycam footage released by the Moab Police Department in Utah.

Brian Laundrie as seen in bodycam footage released by the Moab Police Department in Utah. (Moab PD)

"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," he said. "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."

GABBY PETITO: FBI CLOSES HOMICIDE INVESTIGATION AS IT REVEALS BRIAN LAUNDRIE'S NOTEBOOK CONFESSION

After Laundrie returned to his parents’ home on Sept. 1, the family said nothing publicly about Petito’s death. The family went camping at Fort DeSoto Park, south of St. Petersburg, between Sept. 6 and 8. Petito’s mother reported her missing to police in her New York hometown on Sept. 11.

Reporters witnessed a rainbow overhead just moments after authorities removed Gabby Petito's remains from a campsite in Wyoming's Bridger-Teton National Forest.

Reporters witnessed a rainbow overhead just moments after authorities removed Gabby Petito's remains from a campsite in Wyoming's Bridger-Teton National Forest. (Audrey Conklin/Fox News Digital)

That was a day after Roberta Laundrie allegedly blocked Nichole Schmidt, Petito’s mother, on her phone and on Facebook, according to the lawsuit.

"There were multiple conversations between Brian, his parents, and their lawyer Steven Bertolino before Brian left Wyoming on August 30, 2021," Petito family attorney Richard Stafford told Fox News Friday. "Christopher and Roberta had mutliple opportunities to discloseto Joe, Nichole or the authorities that Gabby was no long alive and to direct them to her body."

He added that the Laundrie parents "must be held accountable."

BRIAN LAUNDRIE FOUND: PARENTS MAY HAVE JUST MISSED UNCOVERING REMAINS THEMSELVES

"A normal mother and father would, after having the girl living with them for that length of time, would obviously ask the question, where is she?" said John Kelly, a criminal profiler who has been following the case. "And that’s where it gets real weird. Would he tell them that he killed her? Would he tell them that something happened to her? Would he tell them that she ran off?"

The lawsuit also alleges that during this time, the parents were attempting to arrange a way for their son to flee the country. He left their home in the days following the missing person report and was ultimately found dead of a self-inflicted gunshot wound in a swampy park nearby in late October. Fox News Digital was the only media present in the reserve with Laundrie’s parents and two members of law enforcement at the time.

His body had been there for weeks after floodwaters complicated a massive FBI-led search.

GABBY PETITO HOMICIDE: TIMELINE OF DISAPPEARANCE WITH BRIAN LAUNDRIE

In his final words, Laundrie admitted to killing his former fiancée Petito in a remote Wyoming campground, according to the FBI, based on entries investigators found in the notebook recovered near his skeletal remains in a Florida swamp in October. They did not describe the contents of the notebook until three months later.

The FBI also at the time announced previously undisclosed details about her death, which a Wyoming medical examiner ruled a homicide by manual strangulation last fall. She had suffered blunt force trauma to the head and neck.

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Court documents show the Petito and Schmidt families are seeking more than $100,000 in damages for alleged negligence, pain and suffering. They are demanding a jury trial.

Fox News’ Laura Ingle, Heather Lacy and Sarah Rumpf contributed to this report.