What's Next for Gabby Petito Homicide Investigation After Brian Laundrie's Remains Are Found?

Authorities will comb through Brian Laundrie’s notebook and other items found near his remains, experts say

Investigators still have a lot to do in the Gabby Petito homicide investigation now that the remains of her fiancé Brian Laundrie — the only person of interest named in her case — have been found.

On Wednesday, authorities in Florida found Laundrie's remains in Myakkahatchee Creek Environmental Park, where they'd been looking for the 23-year-old for more than a month.

The body was found next to a notebook and backpack he owned. Authorities haven't said if any other items were found, or what was inside the backpack.

Brian Laundrie. gabby petito/ instagram

Laundrie had been missing for more than a month, having last been seen six days before Petito's body was found in Wyoming's Grand Teton National Park on Sept. 19.

Petito, 22, died from strangulation while on a two-month-long, cross-country road trip with Laundrie. He was named a person of interest in her disappearance on Sept. 15 — after returning home alone in Petito's van on Sept. 1 without her, say authorities.

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Though Laundrie is dead, many unanswered questions remain.

Here are what legal experts say are authorities' next steps:

Solving Petito's Homicide

Despite the assumption of many that Laundrie killed Petito, former FBI special agent Stuart Kaplan, who is now an attorney, tells PEOPLE the case is still open, legally.

"We can surmise, we make an assumption, but right now the responsible party for the homicide of Gabby Petito, arguably, is still unsolved," Kaplan says.

Local and state authorities in Florida and Wyoming are still working with the FBI to figure out exactly what happened to the couple who were traveling around the country documenting their adventures on YouTube.

"I think that the FBI is coordinating local law enforcement's efforts," says Kaplan.

Investigating Laundrie's Cause of Death

Ascertaining Laundrie's cause of death will be challenging because his remains were found in an area that was previously underwater.

Dental records confirmed that human remains found last week belong to Laundrie.

But since autopsy results were inconclusive, his remains will be further examined by an anthropologist, Laundrie family attorney Steven Bertolino has told PEOPLE.

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"That seems to make it that much more difficult, because you're now asking someone to try to piece together, potentially, the cause of death," says Kaplan. "Obviously with the degradation or the decomposition of the body, we may never know the actual cause of death.

"Absent a gunshot wound to the head, where it would've been readily available to see, even by the naked eye, you just may not ever find out what the cause of death was," he says.

Reviewing Evidence Found With Laundrie's Remains

While authorities wait for answers from the anthropologist, they are also closely examining "documents, paperwork and other items" that were found at the scene of Laundrie's death, says Michael Bachner, a former Assistant District Attorney in the Manhattan District Attorney's office who is now a defense lawyer.

"They'll review those to determine ... whether there is a nexus or a tie by Brian Laundrie that conclusively demonstrates or reasonably demonstrates that he was the perpetrator of the death of Gabby Petito," Bachner says.

Authorities will look for a confession, suicide note, or any other kind of message Laundrie may have left behind, says Bachner.

"It's not unusual where someone commits suicide as a result of either guilt or stress to leave some type of a note, either apologizing or explaining," he says.

Charges Against Laundrie's Parents 'Unlikely': Expert

Initially, Laundrie's parents refused to meet with the FBI to discuss Petito's missing persons case, referring them instead to attorney Bertolino, a longtime family friend.

A week later, the Laundrie family reached out to the FBI to alert investigators that their son was missing. They said he was last seen on Sept. 13, after allegedly leaving their home to hike in the nearby Carlton Reserve, which connects to the park where Laundrie was found. They have not done any media interviews and have stayed mum about the case.

On Monday, Bertolino told PEOPLE he has been informed by the FBI they have "everything they need" with respect to the investigation into Petito's death.

Bachner tells PEOPLE that "authorities may be looking into whether or not there were any efforts by the family to either obstruct, or whether the family withheld information, or whether they were at all times honest with law enforcement."

Bachner says he thinks it's "unlikely that the Laundrie family would be subject to any type of prosecution on this, of course, depending on the gravity of what authorities find," he says. "They may find nothing at all."