• Schmidt urged Laundrie's parents to 'tell the truth' about her daughter's death
  • Petito was engaged to Laundrie when she was killed in late August
  • Authorities have yet to find any signs of Laundrie during their search

Gabby Petito’s mother said she believes Brian Laundrie’s parents are withholding crucial information about her daughter’s death and their son’s disappearance.

In an interview with “60 Minutes Australia” that aired over the weekend, Nicole Schmidt, Petito’s mother, called out Laundrie’s parents for keeping information about her daughter’s demise and urged them to “tell the truth.”

"I think silence speaks volumes. I believe they know probably, if not everything, they know most of the information," Schmidt said. "I would love to just, face to face, ask, 'Why are you doing this? Just tell me the truth.'"

Petito, 22, was engaged to Laundrie, 23, when she died. The couple was on a cross-country road trip, which they occasionally chronicled on social media, before Laundrie returned home alone to North Port, Florida, in Petito’s vehicle on Sept. 1.

Laundrie’s parents on Sept. 17 called investigators to report their son missing, saying he went on a hiking trip on Sept. 14 and has not been seen since. However, Jim Schmidt, Petito’s stepfather, argued that Laundrie should be labeled “hiding” instead of “missing.”

"Gabby was missing. There's a lot of other people out there that are missing. He's hiding,” Schmidt said during the interview.

Laundrie is the sole person of interest in the death of 22-year-old Petito, whose body was found on Sept. 19 in Bridger-Teton National Forest in Wyoming. Her death was ruled a homicide, with the cause of death being “manual strangulation or throttling.”

Authorities have issued an arrest warrant for Laundrie for using Petito’s debit card to make a purchase or withdrawal of $1,000 between Aug. 30 and Sept. 1. Investigators believe Petito was killed in late August.

Chris and Roberta Laundrie have refused to publicly talk about the case. On Tuesday, the Laundries repeatedly dodged a throng of media while they were running errands at their local Walmart, AT&T and FedEx stores, according to Fox News.

Over the past weeks, authorities have combed T.Mabry Carlton Jr. Reserve and Myakkahatchee Creek Environmental Park in their search of Laundrie. As of Tuesday, authorities have yet to acknowledge finding any signs of Laundrie during the search.

Gabby Petito, shown here on a police bodycam in Utah, was strangled to death, a coroner has said
Gabby Petito, shown here on a police bodycam in Utah, was strangled to death, a coroner has said Moab City Police Department / Handout