In the latest update on the disappearance of Gabby Petito's former fiancée, the father of Brian Laundrie was at the Florida nature preserve to help track down his missing son at the request of law enforcement.

The manhunt for Brian Laundrie enters its third straight week on Friday. There was a new member of the Brian Laundrie search party – Chris Laundrie, the father of the missing 23-year-old fugitive.

"Chris Laundrie is assisting Law Enforcement today in the search for Brian," a statement from Laundrie family attorney Steven Bertolino said. "Chris was asked to point out any favorite trails or spots that Brian may have used in the preserve.

"Although Chris and Roberta Laundrie provided this information verbally three weeks ago it is now thought that on-site assistance may be better," the statement added. "The preserve has been closed to the public and the Laundries as well but the parents have been cooperating since the search began."

North Port Police said they didn't make the request for the dad to assist with the search, noting that such a request would have come from the FBI – the lead agency on the case.

Chris Laundrie entered the reserve around 10 a.m. and left the park just after 1:30 p.m., according to WTVT.

"There were no discoveries but the effort was helpful to all," Bertolino said Thursday afternoon. "It seems the water in the Preserve is receding and certain areas are more accessible to search. The entire Laundrie family is grateful for the hard work of the dedicated members of law enforcement that have been searching the Preserve for Brian over the last few weeks. Hopefully Brian will be located soon."

Earlier this week, the attorney was asked if Brian's parents believe he is in the preserve or another area, and he responded, "No, they don't believe he's in another area. They believe he is in the preserve."

Gabby Petito's father reveals what he wants to happen to Brian Laundrie

During a "Dr. Phil" interview that aired Wednesday, Gabby Petito's family from Long Island, New York, articulated what has been going through their mind since the murder of their 22-year-old daughter in Wyoming.

"Petito's body was found about a five-to-ten-minute walk from where her van was last seen near the entrance to the Grand Tetons, on the border of Bridger-Teton National Forest," the family said according to WFLA-TV.

"You could see where the rocks had been moved to make the fire ring," said Gabby's stepfather Jim Schmidt. "It's definitely not an area that was heavily trafficked."

Petito's family told host Dr. Phil McGraw that they called and texted Brian's parents when they couldn't get in touch with Gabby, but the couple never replied.

"A normal parent, when you text someone that 'you're gonna call the cops cause you can't find your child' they would reply," Gabby's father Joseph Petito said. "No response. No nothing."

"I do believe they know a lot more information than they're putting out there," Gabby's mother Nichole Schmidt said of the Laundrie parents.

Gabby's family told Brian, "Turn yourself in."

"You're only making it worse. For us, and for himself, and for his family. Let us have some closure," Jim Schmidt said.

"I want to look him in the eyes," Nichole Schmidt said of Brian Laundrie.

Joe Petito said he wants Laundrie found alive so he can spend the rest of his life behind bars.

"I want to see him in a jail cell for the rest of his life where – he's an outdoorsman – being in that concrete cell and he can't go see those trees and hug – and smell the fresh air like that," the grieving father said.

In late September, Laundrie's parents released a statement through their attorney, "Chris and Roberta Laundrie do not know where Brian is. They are concerned about Brian and hope the FBI can locate him. The speculation by the public and some in the press that the parents assisted Brian in leaving the family home or in avoiding arrest on a warrant that was issued after Brian had already been missing for several days is just wrong."

Brian's sister said she has been cooperating with authorities "since day one." Cassie Laundrie addressed the accusations that her parents may have assisted their son during a "Good Morning America" interview that aired on Tuesday.

"I don't know if my parents are involved," Cassie Laundrie said. "I think if they are, then they should come clean."

Cassie also gave a message to Brian, "I would tell my brother to just come forward and get us out of this horrible mess."

"I worry about him. I hope he's OK, and then I'm angry and I don't know what to think," Cassie continued. "I hope my brother is alive because I want answers just as much as everybody else."

Brian Laundrie remains a person of interest in the Gabby Petito case, but has not been named a suspect in her homicide.

The U.S. District Court of Wyoming issued a federal arrest warrant for Laundrie for bank fraud charges. Laundrie reportedly used a debit card and PIN number for accounts that did not belong to him, according to the indictment. He allegedly ran up charges totaling over $1,000 between the dates of Aug. 30 and Sept. 1. A grand jury indicted him for his "use of unauthorized devices."

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