Hugh Pickens writes "The NY Times reports that it is possible to fabricate blood and saliva samples containing DNA from a person other than the donor, and even to construct a sample of DNA to match someone's profile without obtaining any tissue from that person — if you have access to their DNA profile in a database. This undermines the credibility of what has been considered the gold standard of proof in criminal cases. 'You can just engineer a crime scene,' said Dan Frumkin, lead author of the paper. 'Any biology undergraduate could perform this.' The scientists fabricated DNA samples in two ways. One requires a real, if tiny, DNA sample, perhaps from a strand of hair or a drinking cup. They amplified the tiny sample into a large quantity of DNA using a standard technique called whole genome amplification. The other technique relies on DNA profiles, stored in law enforcement databases as a series of numbers and letters corresponding to variations at 13 spots in a person's genome. The scientists cloned tiny DNA snippets representing the common variants at each spot, creating a library of such snippets. To prepare a phony DNA sample matching any profile, they just mixed the proper snippets together. Tania Simoncelli, science adviser to the American Civil Liberties Union, says the findings were worrisome. 'DNA is a lot easier to plant at a crime scene than fingerprints,' says Simoncelli. 'We're creating a criminal justice system that is increasingly relying on this technology.'"