The apparent human remains authorities found Wednesday in a Florida park most likely belong to Brian Laundrie, the family attorney told CNN.
Authorities found a backpack and a notebook they believe belong to Laundrie, 23, near the suspected remains while they were searching in the Carlton Reserve in North Port, FBI Special Agent in Charge Michael McPherson said.
More than a month since his disappearance, McPherson said Laundrie was "a person of interest in the murder of Gabby Petito."
Laundrie has not been charged in the death of his fiancée, although he was indicted for allegedly using two financial accounts that did not belong to him in the days following her killing.
Laundrie family attorney Steven Bertolino told CNN's Chris Cuomo that "the probability is strong, that it is Brian's remains" found by the FBI.
"It's quite sad, you can imagine as a parent, finding your son's belonging alongside from the remains. That's got to be heartbreaking. And I can tell you that they are heartbroken," he said Wednesday.
The discovery comes amid an exhaustive search for Laundrie as authorities try to piece together what happened to 22-year-old Petito-- who was found dead by strangulation after traveling around the western US in a white van this summer and was later reported missing.
A medical examiner arrived on the scene Wednesday, and a formal identification could take a while. A source close to the investigation told CNN that the suspected human remains "appear to have been there a while."
"Based on the condition of the remains, it may take some time to officially identify. It is going to be a very thorough process with the medical examiner," the source said.
The apparent remains were found in an area that has been under water until recently, McPherson said, which could potentially make the identification process take longer.
It was the "very area of the park that we initially informed law enforcement on," Bertolino said, referring to a meeting with law enforcement on September 17.
Brian Laundrie's parents were on the scene when remains were found
Bertolino told CNN that Laundrie's parents -- Chris and Roberta Laundrie -- helped law enforcement with finding some items at the park, which he described as "happenstance."
According to the attorney, Laundrie's parents informed the FBI and the North Port Police Department on Tuesday night that they wanted to visit the park Wednesday morning to search for their son.
Law enforcement met them there and closely accompanied them as they entered the park, Bertolino said.
"As they went further in, Chris ventured off the trail into the woods. He was zigzagging in different areas, law enforcement was doing the same thing. And Roberta Laundrie was walking down the trail," Bertolino said.
"At some point, Chris locates what's called a dry bag. The dry bag is a white bag, laying in the woods, say 20 feet or so off the trail."
Bertolino said, according to Chris Laundrie, the dry bag was in some brambles and he didn't want to it up, because he wanted his law enforcement to see it. However, Bertolino said Laundrie "couldn't find the law enforcement," because they were then out of sight and didn't want to leave the bag there with a news reporter standing nearby, so he picked it up.
"He did meet up shortly with law enforcement, they looked at the contents of the bag. At that time, law enforcement officers showed him a picture on the phone of a backpack that law enforcement had located also nearby and also some distance off the trail," Bertolino told CNN.
"At that point, the Laundries were notified there was also remains near the backpack, and they were asked to leave the preserve."
The suspected remains were found "about 2 to 3 miles inside the Carlton Reserve, or about a 45-minute walk" from the entrance at Myakkahatchee Creek Environmental Park, North Port police spokesperson Josh Taylor said.
When asked why the parents chose to go to the park on Wednesday, Bertolino said it was the first day it was reopened to the public.
"The parents had assumed that the experts, the FBI and all the tracking teams they had would be able to locate Brian based upon the information that we had provided them to the specific areas and trails in the park that Brian liked to visit," Bertolino said. "The park had been closed to the public. There was really no other reason for the Laundries to go search anywhere else.
The young couple traveled together before vanishing
Laundrie has been under public scrutiny in recent months since Petito vanished in September and was later found dead. The family had refused to talk publicly following legal advice, their attorney said.
The young couple was regularly posting on their social media accounts as they traveled across Western states. But those posts stopped in late August, and Laundrie returned solo on September 1 to their home in North Port, where they lived with his parents.
The national search for Petito ensued after her family reported her missing on September 11 after not being able to contact her.
Petito's remains were found in a national forest in Wyoming on September 19 near where the couple had last been seen together. Teton County Coroner Dr. Brent Blue ruled her death a homicide and said she died by manual strangulation.
During the search for Petito, Laundrie declined to cooperate with the investigation into her whereabouts, and soon after, he also went missing. His family told investigators they believed he had gone to a sprawling nature reserve nearby.
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