(NewsNation Now) — A day after a coroner announced Gabby Petito died by “manual strangulation/throttling,” a forensic expert said DNA evidence will be key in finding out who killed her — if any still exists.

“The FBI did collect DNA specimens, we really don’t know whether those specimens are going to reveal anything,” said forensics Professor Larry Koblinsky. “First of all, [Petito’s body] may be so decomposed that the DNA is going to be useless. On the other hand, the likelihood is that there will be DNA present.”

Petito died some time after Aug. 25, apparently while she and her boyfriend, Brian Laundrie, were on a cross-country road trip. The 22-year-old was reported missing Sept. 11 by her parents after she did not respond to calls and texts for several days. Petito’s body was found Sept. 19 just outside Grand Teton National Park in Wyoming.

Koblinsky believes that given the manner of Petito’s death, there could be more DNA evidence available than in other homicides.

“If the hands were on the neck, there’s going to be a transfer of skin cells from the hands and the fingers,” Koblinsky said.

However, Koblinsky noted that Laundrie and Petito were in a relationship and had been driving across the country in a tightly packed van. There’s little doubt Laundrie’s DNA would be present on Petito in some form, so the DNA gathered from the area of her strangulation would ultimately be the most valuable to investigators.

“If you see fingerprint impressions around the neck, that’s the area to take DNA from … under those impressions,” Koblinsky said. “Surely there’s going to be his DNA. Brian Laundrie’s DNA is maybe all over [Petito’s] body. I wouldn’t say that that’s a significant finding. But finding his DNA under those fingerprint impressions on the neck could be damning. And that would be very important to litigation.”

On Sept. 15, Florida authorities say Laundrie was named a person of interest in Petito’s death. Laundrie’s parents, through their attorney, said Oct. 5 they now believe the last time they saw Brian was Sept. 13.

On Sept. 17, their attorney initially told the news media his parents last saw him Sept. 14.