(NewsNation Now) — The remains of Brian Laundrie were sent to an anthropologist because medical examiners could not determine his cause of death, according to his attorney, Steven Bertolino.

Investigators have not said exactly what condition the remains were in when they found them on Wednesday. Sources have told NewsNation they were bones and a partial skull.

Police sources told NewsNation’s Brian Entin they are confident they will “eventually” determine a cause of death.

A forensic anthropologist specializes in getting answers about the end of someone’s life when they are not obvious.

“When human remains or a suspected burial are found, forensic anthropologists are called upon to gather information from the bones and their recovery context to determine who died, how they died, and how long ago they died,” according to the Smithsonian Museum of Natural History’s website. “Forensic anthropologists specialize in analyzing hard tissues such as bones.”

The FBI announced they used dental records to confirm the remains belonged to Laundrie.

Laundrie was last seen on Sept. 13 when he took his family’s car to the Carlton Reserve for a hike. North Port police had said they were monitoring him, but on Friday a spokesperson confirmed there were limits.

“Our intention was to keep an eye on Brian and clearly we missed him going out [to the reserve],” said North Port Police spokesperson Josh Taylor. He said officers could not follow him closer at the time because the investigation was not far enough along.

Laundrie was named a person of interest Sept. 15, two days after he left his parents’ home for the last time.

Bertolino also expressed frustration at speculation that Laundrie’s parents, Chris and Roberta Laundrie, planted his remains and the backpack and notebook that was found nearby.

“Do you really think the Laundries had skeletal remains of their son, you know, in a plastic bag and brought them to present to the [Carlton Reserve]?” Steven Bertolino said on “NewsNation Prime” on Thursday. “Do you realize how ludicrous that is, how aggravating, how maddening it is to even hear those things?”

North Port police also told NewsNation they do not believe there was foul play involved in finding the remains.

With Laundrie dead, some experts are worried there may not be enough evidence to know how Gabby Petito, his girlfriend, died.

“If there’s someone else involved the FBI will investigate that and will see what culpability they have,” Attorney Steven Capriati told NewsNation affiliate WFLA. “The parents of Gabby and attorneys will have answers soon and I hope they do, and I hope law enforcement can bring this case to a conclusion, but I think it’ll take some time.”