The cases, some almost 30 years old, range from a student discovered with a broken neck to two young women who were raped, murdered and dumped by the side of a motorway. They include some of the most baffling and mysterious unsolved crimes - so-called "cold" investigations.
In a technological breakthrough, forensic scientists can now provide DNA profiles of criminals from a single blood cell, a sperm or even from a flake of skin left on a light switch.
Within a decade, forensic scientists believe they will be able to produce a full genetic "photofit" of a suspect's weight, height, facial characteristics, hair and eye colour from a single cell or a drop of blood.
Dave Barclay, a senior scientist at the Forensic Science Service and its co-ordinator at the National Crime Faculty, said: "We are trying to ally new techniques such as DNA to new ways of looking at crime scenes so that we can reinterpret circumstances and try and discover in more detail exactly what happened."
At the forefront of DNA testing is the single-cell technique. A Forensic Science Service spokesman said: "The new procedure is cutting edge. We have only started using it during the past couple of weeks. It's based on the idea of taking DNA from smaller and smaller pieces of evidence ... a speck of blood so small it is invisible to the naked eye, or a fleck of dandruff."
But the service will not offer the new system to police until it has been tested and ratified. A handful of cases are being re-examined in a pilot scheme.
Before more sophisticated sampling was devised, officers used to "tape" bodies, using sticky tape to pick up any hairs that may have been shed by the attacker. The tapes and other hairs from crime scenes were often kept. DNA can be taken from even a dead shaft of hair.
Advances have also enabled detectives to obtain overlooked intelligence from old cases and work out what happened. This technique, called "physical profiling" allows, for example, detectives to calculate where and how an attack may have taken place, or what type of weapon was used and in what way.
These methods are also being used as part of the on-going Operation Enigma investigation, which is examining possible links between unsolved murders of women and killings involving prostitutes.
Among the hundreds of "cold case" inquiries that are benefiting from the new techniques are the killings of:
n Barbara Mayo, 24, who in 1970 was found in woods off the M1 in Derbyshire. She had been raped and strangled. After tests on a sample of the killer's DNA found on Mayo's clothing, police believe the murderer was probably responsible for the killing of Jacqueline Ansell-Lamb, 18, a secretary who died in similar circumstances, also in 1970.
n An unidentified young woman found murdered and dumped in Bedgebury Forest, Kent, in October 1979. She suffered massive head injuries from a beating. The case was reopened last October after forensic science tests were done on stored evidence.
A former lorry driver, in his early 70s, from Kent, was arrested last month in connection with the murder and was later bailed. A report will be sent to the Crown Prosecution Service.Reuse content