A man whose body was found frozen in a Pennsylvania cave in 1977 has been identified by authorities nearly five decades later.

The Berks County Coroner's Office said the body was that of 27-year-old Nicholas Paul Grubb from Fort Washington, Pennsylvania.

Authorities said they worked out the identity of the so-called "Pinnacle Man" after finally tracking down and matching Grubb's fingerprints.

Grubb's body was found frozen in a cave just below the Pinnacle in Albany Township, a hiking area 75 miles (122km) northwest of Philadelphia.

It ends a near 50-year mystery, multiple unsuccessful attempts to identify the frozen remains, and an exhumation five years ago to extract DNA.

The initial post-mortem examination determined that "Pinnacle Man" died from a drug overdose. Police ruled out foul play.

Dental records and fingerprints were taken, but no match was found.

It was nearly half a century later, in August, then a Pennsylvania police detective tracked down Grubb's fingerprints, the Berks County Coroner’s Office said.

They were then submitted to NamUs, a national missing persons' database, and the FBI was able to uncover Grubb's identity in less than an hour.

The coroner's office said the discovery highlighted the "considerable effort" taken to identify unclaimed bodies.

They added that the Pinnacle body had been unsuccessfully compared to around 10 missing people in the last 15 years, and the body's 2019 exhumation for DNA proved similarly fruitless.

Officials were considering re-burying his remains when the discovery of his identity was made, they said.

Grubb, known as "Nicky" to his family, had served with the Pennsylvania Army National Guard, they said, and received an honourable discharge in 1971.

The coroner's office said his family was "very appreciative" of the efforts to identify him.