Police to identify criminals from their breath

Police officers are to be given new advice in preserving crime scenes after scientists developed the technology to identify criminals from traces of their breath.

Police officers are to be given new advice in preserving crime scenes after scientists developed the technology to identify criminals from traces of their breath.

Tiny specks of moisture emitted from the mouth during speech can provide sufficient material to pinpoint a suspect using new supersensitive DNA techniques.

The invisible moisture from breath can be left on telephones or on discarded material used by criminals to mask their faces. Larger droplets will have been deposited if the offender spluttered or coughed while committing the crime.Senior police officers are concerned that crucial evidence is being lost because of a lack of awareness of the scope of the new technology by investigating teams.

Training courses on preserving the invisible evidence are to be devised by experts from the new Central Police Training and Development Authority (Centrex), launched today by the Home Office minister John Denham.

Officers investigating the most serious crimes will need to be aware that they could be contaminating scenes by destroying invisible evidence, even by breathing. In future officers are likely to have to attend scenes clad from head to toe in protective clothing and to wear masks.

Andy Humphreys, head of operations at Centrex, said: "We are moving to a position where it's difficult to see how somebody will be able to avoid leaving a trace when they enter a room if that trace comes from the fact that they are going to have to breathe."

Paul Millen, who is in charge of training police officers in forensic science, said the new DNA techniques were so sensitive that they would require "great discipline" at the crime scene. He said: "At a crime scene where you are going to use these techniques you are going to have to be very careful that you control the scene. You have to wear white suits and gloves and use masks so that you don't introduce your own DNA."

Mr Millen said that research was still under way to see how long DNA from breath and from particles of shed skin "persisted" at a scene and whether it was possible for one person to transfer someone else's DNA to a scene after a handshake or another form of contact. Research by the City of London Police force in conjunction with London's South Bank University has already given an indication of the value of the new technique.

Scientists from the university, completely dressed in protective clothing, took swabs from offices where organised thefts of computer equipment had taken place.

The swabs were sent to the Forensic Science Service in Birmingham, where they were subject to analysis to try to identify DNA from tiny particles. The technique was found to identify a suspect in 50 per cent of cases, compared with 30 per cent in previously used methods. The operation has led to the arrest of 21 computer thieves.

Centrex, based at the national police training college at Bramshill in Hampshire, is likely to become Britain's main seat of learning in policing skills. It will draw into a single entity the police's national crime faculty, national operations faculty and other areas of expertise around the country.