The FBI has identified a serial rapist as the culprit in the sexual assault and murders almost three decades ago of a young couple at a US national park.

Police found Julianne Williams, 24, and her partner Laura Winans, 26, bound and gagged with their throats slashed at their Virginia campsite on 1 June 1996.

The FBI says DNA tests match Walter Leo Jackson, a convicted rapist who died in 2018 aged 70 in an Ohio prison.

Investigators said there is no evidence the victims were targeted because of their sexual orientation.

The young women's family called the authorities after the two failed to return home from Shenandoah National Park.

Williams and Winans, both experienced hikers, were in the park with a golden retriever when they were last seen by park personnel, nine days before their bodies were found near Skyline Resort.

The local FBI office reviewed the case in 2021, and tested DNA evidence from the crime scene.

They got a positive match to Jackson, a house painter who faced charges related to kidnapping, multiple rapes and assaults.

"Those results confirmed we had the right man and finally could tell the victims’ families we know who is responsible for this heinous crime," Stanley Meador, the FBI Richmond special agent in charge of the case, said in a statement on Thursday.

Jackson, originally from the Cleveland, Ohio, area, was a keen hiker and often visited Shenandoah National Park, investigators said.

At the time, the murders were thought to be an anti-LGBT hate crime, and Mr Meador noted that the attack had “sparked shock and fear throughout the community”.

But US Attorney Christopher Kavanaugh said: "Make no mistake, this crime was brutal, this crime was definitely hateful, nevertheless we do not have any evidence" it was a hate crime.

Authorities originally accused another man of the killings.

Darrell David Rice, a computer programmer from Maryland, was indicted for capital murder in 2001.

It was alleged he targeted the couple because of his hatred of women and gay people.

Rice had pleaded guilty in 1998 to attempted kidnap of a female bicyclist in Shenandoah National Park.

But forensic tests ruled him out in the killings of Williams and Winans.