SARASOTA COUNTY, Fla. — Dental records have confirmed human remains found in a park in Sarasota County are those of Brian Laundrie, the FBI confirmed Thursday.

The remains were found Wednesday in the Carlton Reserve and Myakkahatchee Creek Environmental Park, along with a notebook and a backpack belonging to the missing man.

The 23-year-old's remains were found in an area of the reserve that had previously been under water, officials said.

Laundrie was considered a person of interest in the death of his girlfriend, 22-year-old Gabby Petito.

An attorney for the Laundrie family issued a statement Thursday:

"Chris and Roberta Laundrie have been informed that the remains found yesterday in the reserve are indeed Brian’s. We have no further comment at this time and we ask that you respect the Laundrie’s privacy at this time."

Petito was last seen Aug. 30 in Grand Teton National Park during a cross-country trip with Laundrie, her boyfriend. He returned to Florida alone on Sept. 1. 

A Wyoming coroner last week revealed that Petito had died by strangulation, and that Petito's body had been outside for 3 to 4 weeks before it was found.

Peter Massey, a forensics expert at the University of South Florida, said it was not unusual for dental records to result in a quick positive ID, as they did in Laundrie's case.

"If you can find the dental records and you have a qualified odonatologist, then absolutely," he said. "The odds of someone having the same fillings and crowns and all those other — appliances in your mouth are mostly unique."

When it comes to using Laundrie's remains to determine when he died, Massey, who is not directly involved in the case, said it would be difficult to nail down a precise date.

"Big approximations, big approximations," he said. "There are some people who will say it's a very exact science, there are some people who will say it's an inexact science, because of weather, clothing, body type, many, many different facets."

Heat and the fact that it appears Laundrie's remains had been underwater for some time, will also have to be taken into consideration, Massey said.

"All of that's going to play a part," he said.

There are two very important determinations that investigators will try to make next: manner of death and cause of death, Massey said. 

Manner would include things like suicide, homicide, natural and undetermined, he said; the cause would be "anything that creates the cessation of life," like starvation, lack of water, medication, drugs, a weapon, animals and others.

"So the hard part now is it's going to be — depending on the condition of the body, and this was our concern with Gabby — is there enough material here for the medical examiner/coroner to make the determination of the cause and manner of death," Massey said.

A notebook was found near Laundrie's remains, and what it contains — and how much of it is still legible — could go a long way to determining the 23-year-old's mindset, Massey said. Then again, the "why" question may never have an answer, he said. 

"Unfortunately, we don't have this magical scope to look inside somebody's brain," he said.