Geraldine Hughes' body was found in woods in 1973

Three months earlier, Sandra Newton, also 16, failed to return home from a night out with friends in Briton Ferry and her body was later uncovered in a culvert at Tonmawr, Neath.

They had each been raped and strangled and modern forensic techniques has established a link between the three killings.

Mr Kappen lived within five miles of the victims, was married and in his 30s at the time of the attacks - he died of lung cancer, aged 49, 11 years ago.

Detectives revealed Mr Kappen was on a list of suspects at the time of the murders, but there was not enough evidence to bring charges and he was not arrested.

Matched with DNA samples from the body, forensic evidence from the girls' 28-year-old clothes are leading to a "significant breakthrough," police said.

Raped and strangled

Detective Chief Superintendent Wynne Phillips said Mr Kappen was estranged from his wife when he died in 1990.

"We view this development as highly significant and it has led the investigation into a new chapter," he said.

"The investigating team will have a lot of work to do, but we intend to keep the public fully updated at each relevant stage of the inquiry."

Pauline Floyd was 16 when she was killed

Neighbours said Joe Kappen was a likeable man, but a former friend said the bouncer was violent toward men.

Bill Jones told BBC Radio Wales: "He could be a nasty person, you wouldn't want to step on his toes.

"He was not a chap you would wish to fall out with."

Relatives of the suspect refused to comment on Wednesday.

Serial killer Fred West was ruled out of the inquiry after it emerged he had lived close to Llandarcy - where he had worked as a labourer at the BP oil refinery - at the time the teenagers were killed.