Brian Laundrie was 'upset' when he left the family home on September 13, the family lawyer said on Thursday evening, and his father pleaded with him to stay but could not stop him leaving.
Laundrie told his parents Chris and Roberta that he wanted 'fresh air', and was going for a hike at a nearby nature reserve.
On Thursday the FBI confirmed that human remains found the Florida swamp belonged to Laundrie, and that he had been there for some time.
The FBI's Denver office said that a dental comparison on the skeletal remains confirmed they were those of Laundrie, who has been missing from his home in North Port, Florida, since setting out for the hike.
Steven 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.'
Steve Bertolino, the Laundrie family attorney, spoke to NBC News Now on Thursday night
" title="YouTube video player" frameborder="0"
Bertolino begged those camped outside the house to leave.
'I would like America to know that Chris and Roberta Laundrie are parents.
'They have feelings.
'They have children.
'One of their children has been confirmed as dead.
'This is a loss of a loved one.
'People outside their home - go home, give them a break, please go home.
'Even for one night. Please and thank you.'
Laundrie's parents were informed on Thursday afternoonnthat their son's body had been found, and North Port police officers were seen arriving at the house to tell them.
The FBI's statement said: 'On October 2021, a comparison of dental records confirmed that the human remains found at the T Mabry Carlton Jr Memorial Reserve and Myakkahatchee Creek Environmental Park are those of Brian Laundrie.'
Bertolino said the family told him.
'Chris had called me to let me know that police had come to his house this evening to inform them that the remains were positively identified,' Bertolino told NBC News Now.
'Every parent out there knows that getting the news that your child is no longer with you is sad in any circumstances.
'The fact that the Laundries have been subjected to these people outside the front of their house for the last four weeks, and they continue out there today, is just making it more difficult.'
Bertolino said that he was 'angry' that there was speculation the Laundrie family planted evidence in the case.
The human remains found in a Florida reserve in the search for Brian Laundrie were bones, including part of a skull.
It is unclear how long they have been in the area, but they were found by Chris and Roberta Laundrie on their first day of searching.
Two officers were seen arriving at the Laundrie house on Thursday afternoon, to inform the family that dental records confirmed that the body of their son had been found
North Port police officers are seen on Thursday afternoon arriving at the Laundrie house to tell Brian Laundrie's parents, Chris and Roberta, that the human remains found the day before did belong to their son
The two North Port police officers are pictured being invited into the Laundrie house by Chris Laundrie
The officers left the Laundrie house a little while later. Chris and Roberta Laundrie have not been seen since
The officers are pictured leaving the Laundrie home in North Port, Florida, on Thursday afternoon
Laundrie vanished on September 13.
He is the sole person of interest in the murder of his fiancée Gabby Petito, who was found strangled in a remote part of Wyoming six days after he vanished. She had not been seen alive since August 26, when she was traveling with Laundrie in Utah.
They made the discovery of the remains along with a backpack and notebook believed to belong to Brian as his parents, Chris and Roberta, joined them in the hunt for the first time.
Bertolino said 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.'
He said that the Laundrie family's decision to finally join the search had an entirely rational explanation.
'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 to meet them, and accompany them on the search.
The remains found on Wednesday in the search for Brian Laundrie were bones, law enforcement sources told NewsNation on Thursday
The remains were found north of the entrance to Myakkahatchee Creek, in the Big Slough Preserve, off an unpaved trail near a bridge where Brian's parents said he liked to visit. It is four miles north of their home in North Port, Florida
Bertolino told NBC host Tom Llamas 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.'
The search of the park continued on Thursday with cadaver dogs, dune buggies and police cars, but authorities are being tight-lipped on what exactly they have found so far, and what they continue to search for.
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.
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?'
Bertolino said he was angry at speculation that the Laundrie family had planted evidence at the spot where Brian's body was found, and that he had been in contact with the young man while he was on the run
Bertolino said he was angry at the 'nonsensical' theories circulating in the media and on social media.
'Just yesterday on Fox News an anchor was accusing me of communicating with Brian on a burner phone, until his solar power ran out and I could no longer communicate,' he said.
'That was an anchor.
'You had pundits on CNN just last night with all kinds of theories.
'So my anger and my saying when does it stop - when does it stop with all these conjecturists?People who have no first hand knowledge, and specifically with yesterday's events.
'You have people with first hand knowledge telling you how this played out, and yet people still don't believe it.'
In another interview on Thursday night, with NewsNationNow, he grew frustrated at repeated questions as to why the remains were only found when the parents began searching.
'You think the remains were planted?' he asked, growing increasingly angry.
'You really think they had the remains of their son in a plastic bag and took it to the reserve?
'Do you realize how ludicrous that is? How aggravating, how maddening.'
Bertolino also spoke to NewsNationNow on Thursday night, and bristled when asked whether it was strange that the remains were found on the same day the parents started searching
" title="YouTube video player" frameborder="0"
Laundrie vanished on September 13, six days before the body of his fiancee Gabby Petito was found in Wyoming. She had been missing since August 26
Bertolino dodged NBC's question as to whether he regretted not speaking to the police sooner.
North Port police department were reduced to begging him on Twitter to get in touch and assist them.
He said he had not spoken to the FBI or North Port Police or the district attorney since Laundrie's remains were confirmed, and he wished to speak to them before considering whether he should have done things differently.
'There are things that need to be done, I would say wrapped up, before we can say whether things should be done differently,' he said.
Asked whether Chris and Roberta Laundrie could face charges, the attorney replied: 'I have no reason to believe that.'
When asked whether they cooperated in any way to be granted immunity from prosecution, Bertolino replied: 'I can tell you no. There is no truth to that.'
He continued: 'I can tell you conversations were had several weeks ago with the FBI with respect to certain charges.
'When questioned, and when communications were had between myself and the FBI, I think it was realized charges were not appropriate.
'There was never a threat; there was never a coercion, there was never a deal cut.
'There are always conversations about how the case may play out.
The Laundries have been cooperating with law enforcement - both locally and federally - from day one with respect to Brian.'
Chris and Roberta Laundrie are shown arriving home on Wednesday after human remains, a backpack and a notebook were found in the Florida nature reserve where their son Brian is believed to have been hiding for five weeks. The couple have not spoken to the media or to the family of Gabby Petito, their son's fiancée who was found murdered in Wyoming. The couple arrived home to flowers and cards on Wednesday, but there were also hecklers
Sheriffs departments, the North Port Police Department and the FBI are all still at the nature reserve on Thursday
The search of the nature reserve continued on Thursday morning. Authorities held a briefing on Thursday to say they were still working in the reserve but that they had not discovered anything else
There remains a large media presence at the nature reserve on Thursday
A police officer is pictured walking in the Carlton Reserve with what appears to be the dry bag discovered by Laundrie's father in the preserve. The discovery was made on Wednesday, five weeks after he went on the run following the disappearance of his fiancée Gabby Petito. She was found strangled to death in September in Wyoming
Chris and Roberta Laundrie (pictured) alerted investigators on Tuesday night that they intended to search Myakkahatchee Creek Environmental Park for their son on Wednesday morning. The FBI and North Port Police Department agreed to meet them at the park
Brian Laundrie, 23, is the sole suspect in the murder of his 22-year-old fiancee Gabby Petito. Her strangled body was found in September, weeks after she was last seen alive. The pair were on a cross-country camper van trip when she vanished and he went home in September
The remains and backpack were found near a bridge between Myakkahatchee Creek Environmental Park and the Carlton Reserve, just four miles north of Brian Laundrie's home, just a mile or two into the park. The Laundrie parents say they told the police that it's where Brian might have been, but the portion of the land was submerged in water when cops first searched it in September
Lee County Sheriff Carmine Marceno spoke briefly to the media on Thursday to say the search was ongoing
Lee County Sheriff Carmine Marceno and North Port Police Department Chied Todd Garrison address the media outside the Myakkahatchee Creek Environmental Park in North Port
