Family's renewed hope for son who vanished 39 years ago after anonymous letter claims to know why he disappeared 

An American couple whose son vanished 39 years ago have been sent a letter that claims to know the reasons behind his disappearance.

The letter was sent to Carol Ross, 78, and her 80-year-old husband Bernard Ross Sr almost four decades after Bernard 'Bunny' Ross Jr, then 18, was last seen.

The anonymous writer alleged to have key knowledge of the circumstances surrounding their son going missing, linking Bunny's disappearance with a story in a local newspaper.

Carol Ross, 78, and her 80-year-old husband Bernard Ross Sr received the note to their home in Portland 39 years after Bernard 'Bunny' Ross Jr (pictured before he went missing), then 18, was last seen

Police have since renewed their interest in the case, believing the tip-off to be a genuine fresh lead to find Bernard, who would now be 57.

He was living with his parents in Fort Kent, Maine, when he vanished on May 12, 1977.

He took the family car from their home early that morning and drove it to his aunt's house in Presque Isle, where he is said to have taken another vehicle 'without permission'.

That car was eventually found more than 20 miles away in Ashland. Ross was last seen walking on Realty Road near the border between the towns of Ashland and Portage.

An artist's impression of how 'Bunny' may look now, aged 57

'I think the community was shocked,' the Bangor Daily News quoted his father, Bernard Sr as saying last week.

His mother Carol said: 'People had a hard time because there were no answers... It's not like there was a death. It was the unknown. There was always the hope that he'd walk through the door one day.'

She admitted that Bernard, who was one of six children, was 'going through some ups and downs' around the time he went missing.

The couple moved to Gorham, Maine, in 1981 - four years after he disappeared.

They lived there for 20 years when they decided to move to Portland.

'I've never had anything like this happen in my career,' Police Lt Troy Gardner of Maine State Police said in Portland, where Ross' parents now live,

He went on to tell the Portland Press Herald: 'Basically, all we're doing is extending an olive branch, saying we want to make contact with this person.

'Of course, there's no way of knowing whether the letter's truthful or the information is accurate, but we are asking for whoever wrote the letter to please contact us.'

He made it clear that there was a chance the letter was a hoax adding that if it was, 'that's a horrible thing to do to somebody who's been missing their son since 1977'.

Lt Gardner confirmed the letter was sent to Mr and Mrs Ross but did not disclose details such as whether it was handwritten, how long it was or even what the writer claimed had happened to their son.

Bunny was living with his parents in Fort Kent, Maine, when he vanished on May 12, 1977 (pictured, the police station in his hometown)

He said the police want to find out more about letter's author and try to discern whether its authentic before they release any more information.

'There's always been the hope or assumption that he's alive out there,' Gardner added.

'There's been nothing to suggest he's not alive. The other side of that is that he's been missing since 1977, and that's a long time to go without contact with family.'

• Anyone with any information should call the state police at 1-800-924-2261 or 532-5400 and ask to speak with Sgt. Darrin Crane.