U.S. scientists have elaborated technology that can spot trace amounts of explosives, drugs or many other substances through fingerprints.

According to chemist R. Graham Cooks of Purdue University in West Lafayette, Ind., if a person touched cocaine, explosives or other materials, there could be enough left in a fingerprint to identify them.

The progress in forensics comes from combining new techniques, like those used in the investigation of anthrax, with existing techniques, like those involved in the Ramsey case, said Max M. Houck, director of West Virginia University's Forensic Science Initiative.

The FBI said this week that development in genetic research permitted police to trace the anthrax used in the 2001 attacks to a certain flask of spores.

In the killing case of 6-year-old Ramsey in 1996, it was only this year that prosecutors informed that a new series of tests indicated to an unknown attacker, clearing family members of suspicion.

Although the testing technique used in Ramsey's case was not new, as Houck said, prosecutors found out it could be relevant to their case in a 2007 West Virginia University course.

According to Cooks, the testing method, discussed in Friday's edition of the journal Science, could be available in a year or two, as quoted by the Associated Press.

He explained that substances like cocaine and military explosives have the tendency to be hard to get off the fingers. If someone who has manipulated them later handles something hard like a file or plastic binder, it will transfer the chemicals, he said.

The chemicals are found at the points of the fingerprint's ridges, so what is then on the hard surface is the fingerprint in chemical. Thus, police can not only identify the individual from the print, but also link the person and the drug or chemical, Cooks concluded.