Gabby Petito and Brian Laundrie

Gabby Petito and Brian Laundrie are seen in this Instagram post.
Brian Laundrie's autopsy is inconclusive, Florida authorities have said, and the remains are now being sent to an anthropologist to try and determine how he died. No manner or cause of death was determined.

'I can confirm that the remains were being sent to an anthropologist for further evaluation,' Steve Bertolino, the Laundrie family lawyer, told DailyMail.com.

Laundrie's remains were found on Wednesday in the T Mabry Carlton Jr Memorial Reserve. The 23-year-old was last seen on September 13, his parents said, when he left to go for a hike.

Laundrie was the sole 'person of interest' in the murder of his fiancee, Gabby Petito, who was found dead in Wyoming.

The pair had been on a road trip and documenting their travels on social media.

brian laundrie remains found florida swamp

Location where Brian Laundrie's remains were found
Laundrie's remains were found on Wednesday in the T Mabry Carlton Jr Memorial Reserve.

The 23-year-old was last seen on September 13, his parents said, when he left to go for a hike. Laundrie was the sole 'person of interest' in the murder of his fiancee, Gabby Petito, who was found dead in Wyoming. The pair had been on a road trip and documenting their travels on social media.

An extensive manhunt was staged for almost five weeks, with a particular focus on the Carlton Reserve because Laundrie's Ford Mustang was parked at the park, and he was known to go hiking there.

But the search was incredibly difficult due to the swampy conditions, with the park full of alligators and snakes, and much of it underwater.

Laundrie's remains - said to include part of a skull - were found in an area of the swamp which until recently were under several feet of water. It had been expected that pinpointing his cause of death would be complicated, because the body had reportedly lain in the water for some time.

'Forensic anthropologists are called upon when the environment has ravaged or removed the soft tissue,' said Dr Heather Walsh-Haney, speaking to WPBF News. 'Soft tissue markers that the forensic pathologist would use.'

A forensic anthropologist was also required to determine how Petito died. Her body was found on September 19, and the autopsy results were announced on October 12.

She said the longer the remains are left outside, the greater the chances that evidence is lost.

'Four weeks is a long time for human remains to be out in the wilderness,' Walsh-Haney said.

Bertolino said on Thursday night that he did not know how Laundrie died.

'I don't want to speculate,' he told NBC News Now.

'I try not to do that. I would hope people would stop doing that as well, especially with respect to this case.

'And in respect to the cause or how Brian came to be dead I don't know.

'We'll wait, if possible, for some kind of cause of death from the experts.'

Petito and Laundrie embarked on a cross-country trip earlier this summer with a plan to document it all on film for their social media channels.

But their loved-up Instagram persona was a far cry from the combative relationship that was playing out behind the scenes.

Just a few weeks before she vanished, police in Moab, Utah, were called to the pair's van after fellow travelers saw Laundrie hit Petito. They were separated for the night, and Petito was deemed to be the aggressor. August 26 was the last time anyone saw or heard from Petito.

Laundrie returned to his parents home on September 1. At first, they told officers they last saw him on September 14. They later said it was in fact September 13, when he told them he was going on a hike in the reserve and never returned.

He had been on the run ever since and his parents refused to speak publicly about the case or help Petito's parents.

Laundrie's sister Cassie then began giving media interviews, saying her parents had kept her in the dark and pleading with them to tell investigators what they knew.

The Petito family retrieved her remains from a mortuary in Wyoming last week.

Chris and Roberta Laundrie, Brian's parents, joined the search for their son on Wednesday - and on their first day searching, his body was found.

They were seen walking with an officer, who was overheard saying: 'I think we might have found something.'

The officer then emerged with a bag that contained articles belonging to Laundrie.

Social media speculation was rampant that Chris and Roberta - who initially refused to cooperate with police, referring them instead to their lawyer - had somehow planted evidence.

The case has gripped America, and many following the case thought it was strange that the four-and-a-half week hunt, with all the resources of the U.S. government agencies, should only be successful on the day the family begun assisting. But Bertolino has angrily denied any suggestion that the Laundries were involved in an elaborate plot, and said they decided to get involved on Wednesday because the park had just reopened.

The Myakkahatchee Creek Environmental Park is situated on 160 acres of heavily wooded land and connects to the 25,000-acre Carlton Reserve.

'I think the prompt was that the park was finally opened to the public,' said Bertolino.

'My understanding is that it was opened either on Tuesday or Wednesday.

'And Chris and Roberta decided that since it was open they wanted to go and look for Brian by themselves.

'After speaking with me I told them I wanted to notify law enforcement so we would have no issue.

'I did text my contact at the North Port Police Department and the response I got was 'Thank you for the heads up'.'

He said that the police were waiting for the Laundrie family outside the park at 7am on Wednesday to meet them, and accompany them on the search.

Bertolino told NBC host Tom Llamas on Thursday evening that he was furious people were speculating that there was something sinister about the body being found on the first day the parents joined the search. Bertolino lashed out at 'John Q public' who refused to believe that the Laundries had nothing to do with their son's disappearance.

'I am a little bit angry that people are even speculating this way,' Bertolino said.

'Primarily because it's not just the Laundries - it's local police department, it's the FBI, it was an independent news person who happened to be there filming.

'And that's all fortunate that police were there and the film crew were there.'

Bertolino emphasized that the FBI said that the area where Laundrie's remains were found had been under water for some time.

'The FBI put out a statement and he said listen, we had searched the area several weeks ago and it was all under water.

'There have been numerous people who said it was waist-deep under water.

'People with first-hand knowledge of the conditions of the park have said that this was under two to three feet of water and yet still John Q public can't get it in their head that this area was inaccessible, and the items that were located yesterday perhaps couldn't be seen.

'We're not just saying it, I'm not just saying it, the FBI is saying it, everyone is saying it, and yet these platforms are running amok with these ludicrous and, I have to say, nonsensical theories of the parents planting things there.

'I mean, enough is enough.

'When does it stop?'

Laundrie was reported missing by his parents on September 17 after claiming they last saw him three days prior. Bertolino said they last saw him four days prior, on September 13. Laundrie's whereabouts have been unknown ever since.

Bertolino, who has known the family for 25 years, said that Chris and Roberta did not know their son would disappear.

'What I can tell you is that Brian was very upset when he left,' he told NBC News Now.

'And Chris conveyed to me several times that he wished he didn't let him go but he couldn't stop him.

'This has been a painful saga for them since September 13.

'It's been a long haul.

'But Brian was a grown man, a young man, 22 years old; he wanted to walk out the door, he walked out the door.'

Federal investigators issued an arrest warrant for Laundrie on September 23 for 'use of unauthorized access device' last month after alleging he used a Capital One Bank debit card that wasn't his.

Until Wednesday, there had been no signs of Laundrie at the Carlton Reserve in Florida, the area his parents cite as the last place he was seen.

Last week, North Port police noted there was 'nothing to suggest' whether Laundrie was dead or alive.

Reality tv star Dog the Bounty Hunter joined in the search, adding to the media circus, and claimed that he had received hundreds of tips from people claiming to have seen Laundrie alive.

Officials claimed no one had seen him in the reserve and search teams didn't find any physical evidence of his presence in the area.

Lee County Sheriff Carmen Marceno held a short press conference on Thursday afternoon, but he mostly thanked and praised his law enforcement colleagues for working in 'treacherous conditions'.

'Today I got to see the treacherous conditions they were working under,' Marceno said.

'We're talking about water levels up to the chest area, rattle snakes, moccasins, alligators.

'These are very, very difficult conditions.

'You're searching in areas where you can't just walk up and look. It's not like you're searching a house or a car.

'These areas are huge and they are covered by water.

'It is challenging times. I know everybody wants to know exactly what's going on every second possible. All of America is watching.

'But we will never jeopardize an investigation to give that information out until the time is right. I want to reiterate, things change by the second, by the minute,' he said.