Former Federal Bureau of Investigation Deputy Director Andrew McCabe believes the parents of Brian Laundrie -- the fiancé of Gabrielle 'Gabby' Petito and the lone person of interest in her death -- acted suspiciously throughout the search for their son prior to his remains being discovered earlier this week.

McCable told CNN that Chris and Roberta Laundrie had "conducted themselves in a very odd way that's generated a lot of suspicion right from the beginning," noting that their recollections of key events have been inconsistent with law enforcement authorities' versions.

On Friday (October 22), former FBI agent Stuart Kaplan told DailyMail exclusively, "There's no doubt that Brian Laundrie's parents are fully engaged with law enforcement," adding, "I do believe that there was some sort of agreement where they accepted immunity in exchange for their full cooperation."

Retired FBI agent Jennifer Coffindaffer told DailyMail that if the Chris and Roberta Laundrie could face obstruction of justice charges if they had any knowledge of their son's actions or whereabouts, but authorities would need concrete evidence to prove such.

"That evidence could include text messages telling him to run or telling him they were going to destroy evidence,' Coffindaffer said. "There's no blood involved in a strangulation but there could be some cells on his clothing. I think the strongest possibility would be an obstruction charge on the cleaning of the Petito van."

Without evidence, however, prosecutors cannot force the Laundries into revealing any possible information their son told them during the 12 days between his return to Florida from his cross-country trip without Petito and his own eventual disappearance.

"They can't be compelled. But you would hope, especially since now that it appears their son is dead, that if they are decent people they will disclose what they know," Coffindaffer said. "The guilt builds and I would not be surprised at all if one of them came forward, eventually, although it could take a long time."

On Thursday (October 21), the FBI confirmed that human remains found in Florida on Wednesday (October 20) are those of Brian Laundrie, the lone person of interest linked to Petito's death.

“The FBI is grateful for the tremendous investigative support from our partners: North Port Police Department, Sarasota Police Department, Jackson Police Department, Charlotte County Sheriffs Office, Lee County Sheriffs Office, Sarasota County Sheriffs Office, Teton County Sheriff's Office, Teton County Search and Rescue, the Florida Wildlife Commission, the National Park Service, and the U.S. Forest Service,” FBI Denver announced in a news release shared on its verified Twitter account.