(CNN) -- What appears to be human remains and items belonging to Brian Laundrie, including a backpack, have been found in the Carlton Reserve in North Port, Florida, according to FBI Special Agent in Charge Michael McPherson.
Another one of the items found was a notebook belonging to Laundrie, who McPherson said was "a person of interest in the murder of Gabby Petito."
The apparent remains were found in an area that has been under water until recently, he said.
A source close to the investigation told CNN that the apparent human remains "appear to have been there a while."
The source said "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."
North Port Police Spokesman Josh Taylor said the 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.
The FBI Tampa's Evidence Response Team is on the scene using "all available forensic resources" to process the area. According to McPherson, it's likely the team will be on the scene for several days.
"I know you have a lot of questions, but we don't have all the answers yet," he said reading a statement for the media.
Brian Laundrie's parents, Chris and Roberta Laundrie, were in the park when the discovery took place, family attorney Steve Bertolino said.
"Chris and Roberta Laundrie were at the reserve earlier today when human remains and some of Brian's possessions were located in an area where they had initially advised law enforcement that Brian may be," Bertolino said. "Chris and Roberta will wait for the forensic identification of the human remains before making any additional comments."
The discovery comes 37 days after Laundrie, the fiancé of Gabby Petito, was reportedly last seen by his parents.
Earlier, the Sarasota County medical examiner and a cadaver dog were called to the park and aerial footage showed activity in the Carlton Reserve near the Myakkahatchee Creek Environmental Park where Laundrie's car was found parked in September.
Laundrie's parents had informed the FBI and the North Port Police Department Tuesday night that they intended to come to the park on Wednesday morning to search for him, Bertolino said earlier. Law enforcement met them there Wednesday morning, he said.
The Sarasota County Medical Examiner was called to the scene, and the Pasco County Sheriff's office said a cadaver dog and two spotters were also on site. The Sarasota County Sheriff's Office Emergency Response Team and the Lee County Sheriff's Office were also now on scene along with a mobile unit.
The discovery comes amid an exhaustive search for Laundrie that has now stretched over a month and as authorities try to piece together what happened to Petito.
The Myakkahatchee Creek Environmental Park is on 160 acres of heavily wooded land in North Port, Florida, with trails and a camping area. The park connects to the Carlton Reserve, a 25,000-acre nature reserve that has been the primary search location for investigators.
Searchers had previously used swamp buggies, divers and airboats to scour the swampy terrain, but the area has dried out recently due to clearer weather.
How we got here
Petito, 22, and Laundrie, 23, traveled around the western US in a white van this summer, all while regularly posting photos and stories to their social media pages. Those posts abruptly stopped in late August, though, and Laundrie then returned by himself to their home in North Point, where they lived with his parents, on September 1.
Petito's family, unable to get in contact with her, reported her missing 10 days later, launching a national search. 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.
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 that she died by manual strangulation.
"We believe this was strangling by a human being," Blue told CNN's Anderson Cooper.
Laundrie has not been explicitly connected to Petito's homicide, but he is the subject of a federal arrest warrant for unauthorized use of another person's debit card in the days after Petito last spoke with her family.
Though their social media posts appear idyllic, their relationship was full of tension and conflict in recent months. Petito called her mom regularly, and those conversations appeared to reveal there was "more and more tension" in Petito's relationship, according to a police affidavit for a search warrant of an external hard drive found in the couple's van.
In addition, the couple was involved in a domestic dispute and were stopped by police in August in Moab, Utah, after a 911 caller told dispatchers he saw a man hitting a woman, according to audio provided by the Grand County Sheriff's Office.
In a report from Moab police, another witness told police he saw the couple arguing over a phone. The witness said that when Laundrie got into the van, Petito appeared to hit him in the arm and then climbed through the driver's side door as if he had locked her out, the report states.
After interviewing Petito, Laundrie and the witness, the officers describe the incident as an argument that turned into a physical fight involving pushing and scratching.
™ & © 2021 Cable News Network, Inc., a WarnerMedia Company. All rights reserved.