MIAMI – New details have surfaced in the lawsuit filed by the parents of Gabby Petito.

The Petitos amended their lawsuit, alleging during the search for Gabby that Brian Laundrie’s parents knew their son had killed her and knew “the whereabouts of the body.”

Petito disappeared while on a cross-country trip with her fiancé, Laundrie.

Laundrie returned to Florida alone.

Petito’s body was found in Wyoming last September, a little more than a week after her family reported her missing.

A coroner ruled she died by strangulation.

Laundrie later took his own life.

Authorities say they found a notebook that contained his confession to Petito’s murder.