Body found in US national park identified as missing Gabby Petito

A body found in a US national park in Wyoming was identified as Gabby Petito, 22, the "van life" traveller who went missing during a road trip with her fiance, the FBI said on Tuesday.

A local coroner had ruled her death a homicide, the bureau said.

"Teton County Coroner Dr Brent Blue confirmed the remains are those of Gabrielle Venora Petito, date of birth March 19, 1999," the Denver office of the FBI said.

"Coroner Blue’s initial determination for the manner of death is homicide. The cause of death remains pending final autopsy results," the FBI said.

Petito's body was discovered on Sunday in a remote area of Bridger-Teton National Forest, in western Wyoming.

It was less than 300 metres from where a pair of travel bloggers filmed what appeared to be the couple's white van parked along a dirt road near Spread Creek on the evening of August 27.

"The FBI and our partners remain dedicated to ensuring anyone responsible for or complicit in Ms Petito's death is held accountable for their actions," FBI Denver Special Agent in Charge Michael Schneider said.

FBI agents are searching for her fiance, Brian Laundrie, 23, as a “person of interest”.

His parents told agents they last saw him a week ago, when he told them he was planning to hike alone in the 9,710-hectare Carlton Reserve wilderness area near North Port.

North Port Police called off their search of the swampy reserve on Monday after “exhausting all avenues” to find Mr Laundrie there.

Investigators spent much of Monday searching the Laundrie home, loading cardboard boxes into a van and towing away a silver Ford Mustang.

The couple left her home state of New York in late June or early July, heading west in her white van with plans to visit America's national parks and document the trip on social media.

Mr Laundrie returned home to North Port alone in the van on September 1.

Ten days later, members of Petito's family reported her missing. Before disappearing, Mr Laundrie had refused to speak with investigators and retained a lawyer.

Witnesses last saw Petito on August 24 as she left a Salt Lake City hotel. She posted her final photo of the trip on social media the next day.

Petito's family believes she was headed to Grand Teton National Park in Wyoming when they last heard from her.

An FBI spokesman said the body was “consistent” with the 167-centimetre, 50-kilogram Petito.

The post mortem examination scheduled for Tuesday is expected to identify the remains and determine a cause of death.

In seeking search warrants, investigators have cited an August 27 text purportedly sent by Petito to her mother, Nicole Schmidt, which describes receiving repeated calls and voice messages from “Stan”, her grandfather.

Ms Schmidt told investigators that message was odd because she would not usually refer to her grandfather by his first name.

Petito's family said a second text message also seemed suspicious.

Last week, police in Moab, Utah, released body camera footage of an August 12 encounter that two of their officers had with Petito and Mr Laundrie during a traffic stop.

Petito sobs in the video as she describes a quarrel with Mr Laundrie that she says became physical at times.

The officers did not detain the couple but insisted they spend that night separately, Petito in the van and Mr Laundrie at a hotel.