Evidence in the killings of Mark Yendell, Philip Green, Glenis Carruthers and Derek Grain will be sent off for testing to discover whether any of the killers left traces of their DNA, the Evening Post can reveal.
If the delicate forensics prove successful, Avon and Somerset's Major Crime Review Team (MCRT) could make significant steps towards closure for the victims' families.
Detective Chief Inspector Mike Carter, review team leader, said these four tragic cases provide the best chance of producing new, valuable leads, following a detailed review of the 24 unsolved murders linked to Greater Bristol.
"If there is a match, that would be compelling evidence. If the DNA evidence is not as good – what we call 'low copy' – we can still check it for similarities against other people."
The MCRT is hoping examination of a blood-stained watch in the case of father-of-two Mark Yendell could lead to a big step forward in the 25-year-old investigation.
The 32-year-old railway worker from Withywood was battered and strangled to death on October 12, 1984.
After more than two days missing, his body was found in the Floating Harbour, having been dragged from the back seat of his red Lancia car on Welsh Back and dumped in the water.
Edward Witts – who had an affair with Mr Yendell's wife Susan – was arrested and questioned in connection with the murder, but was released without charge at the time.
Mr Carter said when he was interviewed he had cuts to his hands, a black eye and cuts on his face, which he said he had got from fixing his car and playing with baby Alexandria Yendell.
Now 27, Alexandria told the Post news that police are still investigating her father's murder has brought back a lot of emotions she had bottled up for years.
"It feels weird," said the mum-of-two, who lives in Hartcliffe. "There was no news for years so I had got to the stage where I thought nothing was going to come of it and the killer had got away with it.
"There is hatred and anger deep down but I've tried not to speak about it. But I've always wanted something to happen and I would love it if something came of this and someone was brought to justice. I don't want to get my hopes up too much."
Police seized a number of items from a suspect in the case, including a metal watch and a long-sleeved shirt. Although there are blood stains between the links of the watch, they were too small to get evidence from before technological advances.
But Mr Carter said: "We're hoping to move forward with this as soon as we can in the new year."
The tragic death of Philip Green on March 31, 1970, is another well-known case.
The 11-year-old, who lived with his parents at Alberton Road, Sea Mills, was brutally killed as he collected lost golf balls at Shirehampton golf course. His body, along with a broken, blood-stained oak branch, was found under trees.
The murder weapon has been examined for DNA evidence, but there was nothing. His belt and shoes had also been examined for fingerprints.
But, for the first time, fibres from Philip's clothes – a Gabardine raincoat, flannel trousers, striped shirt and orange knitted tie – will be tested for DNA.
"It's definitely worth doing as it was a very nasty attack on a young boy," said Mr Carter. "It's probably the last thing we can do in relation to this tragic case, unfortunately.
"We are hoping to see if there are any skin cells that can be examined. The chances are slim, but as with any murder case we will try to exhaust every possibility we can."
Glenis Carruthers was visiting Bristol for her friend's 21st birthday when she was strangled on January 19, 1974.
Police believe the 20-year-old PE student from Bedford left the party in The Avenue, Clifton, either to get some fresh air or to make a phone call at a nearby telephone box.
Zookeeper Alfred Elliot was walking his dogs when he saw what he thought was a "courting couple" on the grass nearby. But the man he saw got up alone and, later, Miss Carruthers's body was found.
The suspect was 20 to 25 years old, had brown shoulder-length hair and was wearing a three-quarter-length denim-type coat.
Mr Carter said: "No one ever saw her leave the party. That's one of the reasons why it's always been a mystery."
The review team is planning to send a string of black beads Miss Carruthers was wearing when she was strangled for DNA testing.
Aerospace engineer Derek Grain was in Bristol developing missiles when he met his untimely end.
The single 39-year-old had been staying at the Unicorn Hotel when he went out in Park Street. He had been seen in Curves and Vicky's nightclubs.
On the morning of November 1, 1980, his body was found in Brandon Lane behind 8 Berkeley Square. Mr Grain had severe head injuries but it is thought he suffocated after being attacked and robbed. His jacket had been removed and his credit cards were scattered on the ground.
The murder weapon was a traffic cone found 80 yards away on Brandon Hill, which provided no forensic breakthrough, but detectives hope tapings from the insides of his pockets could contain skin cells of his killer.
Despite optimism that new technology could crack some of the unsolved cases, there are drawbacks.
To get exhibits examined costs thousands of pounds and even if a DNA profile can be gleaned, there is no guarantee that person will be on the national database, which has only been running since 1995 and covers fewer than one in 10 people.
Mr Carter said: "I believe 70 per cent of the historic murders would have been solved if the police had the technology we have today."
If you have information on the cases call police on 0845 4567000.
