Gabby Petito’s parents and step-parents are having to relive their worst nightmare.

Earlier this year, Nichole Schmidt and Joe Petito, reported their daughter missing after she took a cross-country road trip with her fiancé, Brian Laundrie.

On September 11 Gabby was reported missing and a week later, their worst nightmare became a reality.

“The thoughts that were going through my head were something, something really bad has happened to her,” Nichole recalled.

Gabby’s remains were discovered in Bridger-Teton National Forest on September 19, two days later, the remains were identified as the 20-year-old.

A first look at the Peacock documentary, The Murder of Gabby Petito: Truth, Lies and Social Media,” dropped today on YouTube.

The trailer shows the Petito and Schmidt families reflecting on their daughter’s life, death and legacy.

"It was like every parent’s nightmare," Gabby's stepfather, Jim, recalls in the trailer. "Just like, in a flash of second. She's gone, she's missing."

"It's still unbelievable," Nichole says in the trailer. "I don't understand it."