NORTH PORT, Fla. (NewsNation Now) — A forensic psychiatrist believes Brian Laundrie’s parents are likely “invested in believing him” despite backlash from the community.

“We don’t know what he told them, but what we can expect is that they would be invested in seeing things from his perspective and his account,” Dr. Michael Welner said on Banfield. “So while many people around the country and maybe massing on the family grounds (are) maybe hurling all kinds of anger at the family, we have to remember that they’re not necessarily going to see things the way others see them, because they can always say, ‘We know him more than you do.'”

On Wednesday, Brian Laundrie’s father was planning to join the search for his son but police delayed that plan indefinitely, according to the family’s attorney. Brian was reported missing Sept. 17. His parents now say they last saw him Sept. 13, a day earlier than they’d previously told investigators.

“He may be guilty of the worst of crimes or the most depraved of crimes committed on Gabby, but at the same time, if he’s been in touch with his family, and he’s communicated to them an account, they’re going to be invested in believing him,”  Welner said. “And we have to expect that and we have to respect that because that’s a human nature that comes before any decision to cooperate with law enforcement.”

The manhunt for Brian Laundrie has remained a high-profile investigation since it began last month. The search started two days before his girlfriend, Gabby Petito, was found dead in Wyoming. The two were on a cross-country road trip over the summer, and Petito was last heard from Aug. 27.

Officials have still not revealed how Petito died, other than to say it was homicide. Brian Laundrie has not been charged in her death. He was indicted for bank fraud related to a debit card in Petito’s name investigators believe he used after she died.

NewsNation’s Bobby Oler and Brian Entin contributed to this report.