Dental records show that the human remains found at a Florida wilderness park are those of Brian Laundrie, Gabby Petito's fiance.
The 23-year-old is a person of interest in the killing of Ms Petito, who was reported missing on 11 September by her parents while the couple were on a road trip.
The FBI said the human remains were uncovered in the Carlton Reserve, Florida, in a location that was previously underwater.
His personal belongings were discovered nearby on Wednesday.
Ms Petito's body was found on 19 September on the edge of Wyoming's Grand Teton National Park, which the couple had visited.
Watch: Bodycam footage from officers show couple after argument