New details emerge about one of last known sightings of Gabby Petito and fiancé

Details have emerged about the last known sighting of Gabby Petito and her fiancé together as authorities continue a massive search for Brian Laundrie in a Florida nature preserve for a fifth day.

Laundrie, a person of interest in the 22-year-old New York woman's death, has been missing for more than a week.

A manager at The Merry Piglets Mexican Grill in Jackson, Wyoming, confirmed to NBC News that Laundrie and Petito were there Aug. 27.

The couple had been traveling across the country in their van since July and detailing their journey on social media. The manager of the restaurant said they arrived on foot, without their van.

A coroner has confirmed that remains found in a Wyoming campground on Sunday were those of Petito and said the manner of death is homicide, the FBI announced Tuesday.

The official cause of death will remain pending until final autopsy results are in, according to the statement.

Petito's body was found at the Spread Creek Dispersed Camping Area campground in Bridger-Teton National Forest, 18 days after Laundrie arrived back at his home in North Port, Florida, with the van he and Petito had used to travel across the country.

Laundrie has not been charged with a crime and has not spoken with police. His parents told police he took a backpack to the Carlton Reserve, a 25,000-acre wildlife refuge, on Sept. 14 and has not been seen since.

He drove a silver Ford Mustang to the wildlife area. A lawyer for the Laundries said when he did not return, family members drove the car back from the preserve several days later. Authorities then later towed it from the family's home as evidence.

Karyn Aberts lives across the street from the Laundries' home in North Port and remembers Laundrie and Petito working on their van in the driveway before their trip.

"We heard laughter, we heard them playing music and things like that, so it seems like your normal young couple just kind of hanging out," she told NBC News' Catie Beck.

However, she now has questions for the family.

"Where's your son?" she said. "And why aren't you seeming to be more concerned about where your son is, and supposedly the love of his life, who is now no longer here? How are you handling this, and how are you living with knowing that your son could be the one who's responsible?"

Investigators have spent four days searching the Carlton Preserve with dive teams, canine units and ATVs. After multiple unconfirmed sightings, Laundrie remains at large.