Breakthroughs in forensic science are helping Sussex Police uncover clues to unsolved murders that date back more than 40 years.

Forensic science is advancing so fast that police believe they will soon be able to test particles in a room and tell who has been in there.

Actor Trevor Eve's Waking The Dead is a popular TV series - but its fictional stories are not far from the truth.

Sussex Police, armed with new forensic testing methods, are blowing the dust off unsolved cases and are more hopeful than ever of tracing killers who thought they had got away with murder.

Last year, a man was convicted on DNA evidence of killing a child 33 years ago.

Schoolboy Roy Tutill, 14, was sexually assaulted and killed in 1968 in Surrey.

Farm labourer Brian Field was jailed for life at the Old Bailey after DNA tests proved he strangled the boy.

Sussex Police are hoping for a similar success and, as The Argus reported last week, they are looking again at exhibits and evidence from old, unsolved murders.

They include:

Silvia Taylor, 45, strangled in the off-licence she managed in Nile Street, Brighton, in 1965. The killer stole £62 from the safe
Schoolboy Keith Lyon, 12, stabbed to death in Woodingdean, Brighton, in 1967. The knife used had on it two types of blood - the victim's and possibly the killer's
Playmates Nicola Fellows and Karen Hadaway, both nine, sexually assaulted and strangled in Wild Park, Brighton, in 1986. A jumper found near the scene carries blood stains which might yet reveal the killer's identity.

Detective Superintendent Dave Gaylor, of Sussex Police, said that in the Sixties, the only tests available for the Keith Lyon murder weapon produced blood groupings which were inconclusive for a jury.

He said: "DNA testing could now conclusively prove whose blood is on that knife."

DNA is the greatest breakthrough for crime fighters since fingerprints and Britain is leading the world in its development.

Every person has a unique deoxyribonucleic acid (DNA) make-up unless they have an identical twin.

These complex molecules, which form chromosomes, carry coded instructions for passing on hereditary characteristics.

Anything containing a cell - blood, sperm, the root of a hair - can be minutely examined to expose a person's DNA make up. By matching samples found at a crime scene with suspects' DNA, offenders can be identified beyond doubt.

Prosecutors often present DNA evidence and suggest the odds on the defendant not being responsible were billions to one.

Professor Alex Jeffreys of Leicester University found the way to unlock the body's innermost secrets in 1986.

Scientists Dave Warrett and Peter Gill refined the breakthrough for use in criminal investigations and, since their first successful tests in 1987, the system has been adopted by law enforcement agencies round the world.

When The Argus first reported on early DNA successes in 1991, scientists needed substantial amounts of blood to extract profiles.

A decade on, they can now produce profiles from a sample invisible to the naked eye.

Scenes of crime officers can also extract samples from a variety of surfaces that previously proved impossible.

It is now possible, for instance, to obtain a cell from sweat found within a fingerprint.

There is now a national database for DNA profiles, based in Birmingham, and it proved crucial in nailing Brian Field.

His DNA was not on the database and he escaped justice - until the day he was convicted of a driving offence.

As with all convicted people, his DNA was taken and filed and alarm bells instantly rang when a match with Roy Tutill's killer was made.

Minute particles from body matter, including faeces, can be used to "grow" DNA profiles, to enlarge them sufficiently so they can be read and compared.

Mr Gaylor said the development of a national fingerprint database enables police to compare prints swiftly with millions from across the country.

Modern extra-strength glue is used to lift prints from difficult surfaces.

Murder rooms can be sealed and with the use of chemicals and ultra violet light, blood stains and other evidential marks can be highlighted.

Finding offenders responsible for crimes carried out many years ago carries ramifications, especially for the families of victims. They have to be considered, consulted and informed.

Mr Gaylor recently completed a report, Getting Away With Murder, for the Home Office, which focuses on how to treat families, the media and the investigations themselves.

He said: "It is not just a case of finding a few new pieces of evidence. The process needs managing.

"Advances are happening all the time and their development is running at a very quick pace.

"I don't believe it will be long before we can tell whether someone has entered a room by testing particles.

"The science is becoming more sensitive but that might not always be helpful, especially when the complex science has to be explained to juries for them to appreciate the significance of a piece of evidence.

"Having said that, new advances are giving us a greater chance of bringing to justice serious offenders who have paid no price for their heinous crimes.

"I am delighted we can now look again at these cold cases and I will be even more pleased if culprits can be brought before the courts."