Brian Laundrie's remains were sent to an anthropologist "for further evaluation" after autopsy results came back inconclusive, the family's attorney said.
"No manner or cause of death was determined," the lawyer, Steven Bertolino, said in a statement to NBC News.
Bertolino said he was not given a timeline for when the anthropologist will conclude the evaluation of Laundrie's remains, which he said will ultimately be cremated.
Bertolino added that Laundrie's family has no immediate plans for a funeral, although it may decide on a private ceremony later.
"The family is grieving privately somewhere in Florida," he said.
Human remains were found in Florida's Carlton Reserve on Wednesday after more than a month of searching for Laundrie, who was a person of interest in the disappearance of his fiancée, Gabby Petito, before her body was discovered in Wyoming.
The remains, described as "skeletal" by the North Port Police Department, were confirmed to be Laundrie's after a review of dental records, officials said Thursday.
According to the FBI, the remains were found alongside personal items belonging to Laundrie, such as a backpack and a notebook.
His parents helped lead the FBI and North Port police to Myakkahatchee Creek Environmental Park, Bertolino has said.
He has rejected the notion that the Laundries knew their son might disappear or that they struck a deal with prosecutors to help in the search. He said that, as their attorney, he had advised the parents not to speak with law enforcement.
The Carlton Reserve and neighboring Myakkahatchee Creek Environmental Park, which are connected to each other, are short drives north of the Laundrie family home.
Petito, 22, and Laundrie, 23, were traveling across the country, chronicling their journey in their van on social media. But Laundrie returned to his parents' North Port home without her on Sept. 1, authorities have said.
During the search for Petito, police in Moab City, Utah, released body camera video capturing a distraught Petito after an alleged physical altercation with Laundrie.
Petito's body was discovered Sept. 19 at the Spread Creek Dispersed Camping Area in Bridger-Teton National Forest in Wyoming. Petito had been dead for at least three weeks, and her death was ruled a homicide by "manual strangulation," the coroner said.
Laundrie had been missing since mid-September, when, his parents said, he went hiking in the Carlton Reserve and never returned. The 25,000-acre wildlife refuge was closed for extensive searches and reopened only last week.
An arrest warrant was issued after authorities said Laundrie used Petito's debit card without permission. He was a person of interest in the case and was not charged with Petito's death.
The Petito case has generated enormous public interest, but it has also raised uncomfortable questions about the unequal media and law enforcement attention given to missing white women compared to missing people of color.