Human remains found in a Florida park Wednesday are Brian Laundrie's and consisted of bones, Fox News has confirmed. 

A source familiar with the investigation told Fox News Digital Thursday that the skeletal remains were recovered within the Myakkahatchee Creek Environmental Park Wednesday morning near belongings that appear to have been Brian Laundrie's, including a notebook and a backpack. Laundrie was last seen in mid-September when he left for a hike in the park. 

On Wednesday, Laundrie's parents, Chris and Roberta Laundrie, met law enforcement at the park and searched a trail Brian was known to frequent and discovered what appeared to be his belongings, authorities have said. 

The FBI confirmed Thursday evening that the discovered remains were Brian Laundrie’s, adding that his dental records were used to make that confirmation.

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On Thursday, famed forensic pathologist Dr. Michael Baden told Fox News Digital that a dental record comparison can provide "an immediate determination" once the FBI has collected the necessary information from a person's dentist.

Baden also told Fox News Digital that even when human remains are "skeletonized … still, usually there's enough soft tissue remaining" for DNA tests and toxicology examinations. 

The decomposed body could, however, make the cause of death "more difficult to determine" and could possibly "interfere" with the time of death determination, Baden noted. 

When asked if a body that had been submerged in marshy water for four to five weeks could deteriorate so quickly, the Fox News contributor said no, explaining that a body "would not skeletonize that quickly."

"In order to be skeletonized in this short period – that's within five weeks under these circumstances – it is largely secondary to animal activity," Baden said, mentioning the possible interference from rodents, alligators or bugs. "If it were just left out in the open in the worst conditions, the body might bloat up and there'd be a lot of a lot of destruction of soft tissues ... [but] the body wouldn't be skeletonized."

Chris and Roberta Laundrie said Brian, 23, left his family’s North Port, Florida, home on Sept. 13 to hike in the Myakkahatchee Creek Environmental Park, located alongside the T. Mabry Carlton Jr. Memorial Reserve. The Laundries' attorney had initially identified the date of Brian's disappearance as Sept. 14 before changing the timeline weeks later. 

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Laundrie and his 22-year-old fiancée, Gabby Petito, left for a trip in mid-June with the plan to visit national parks in her white converted Ford Transit. The couple met years earlier on Long Island, New York, where they grew up, and later moved into a North Port home with Brian’s parents.

Petito’s body was discovered in Wyoming on Sept. 19. She died of manual strangulation, according to investigators. 

Laundrie had been a person of interest in Petito's murder.

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Fox News' Audrey Conklin contributed to this report.