In a candid interview with "60 Minutes Australia," the family of deceased YouTuber Gabby Petito offered harsh words for her missing fiance Brian Laundrie.

“We want vengeance and justice, and for him to pay for his crimes," said Jim Schmidt, Petito's stepfather said. Petito's mother, Nichole Schmidt, said she wants Laundrie to be in "a cell for the rest of his life.”

Petito's stepfather and mother spoke glowingly of Petito, who died in September at age 22. 

Jim Schmidt said Petito "was beautiful, she was creative, she was artistic, talented, a genuine person. We all loved her so much." Nichole Schmidt described her daughter as "genuinely happy."

They described Laundrie as "very polite and quiet."

Nichole Schmidt said that she felt that Petito was safe on the trip "because she was with Brian and I felt like she was O.K. I thought he would take care of her." She also said that Laundrie came off "like a nice guy."

Nichole Schmidt was critical of Laundrie's family for their perceived lack of cooperation in the investigation into Petito's death. 

“I think silence speaks volumes ... Why are you doing this? Can you just tell me the truth?” she said.

There has been an intense manhunt for Laundrie, who has been missing for several weeks. He is believed to be the last person to have seen Petito alive. 

Petito and Laundrie had documented their cross-country trip in a van on social media.

Petito’s remains were found in Wyoming. A coroner determined that Petito died from manual strangulation.