This is why we should have capital punishment...

One in every hundred forensic tests performed on the DNA of suspected criminals may give a false result, according to the first research of its kind into laboratory error rates.

The study is the first evidence of widespread mistakes in the sophisticated system of tests. DNA testing is widely used to convince juries of a suspect's guilt or presence at the scene of a crime, and was thought to be almost flawless.

The findings will shock British DNA laboratories, which deny that errors exist.

Statisticians in Austin, Texas, gained access to the first accuracy tests carried out on DNA laboratories, which were conducted anony-mously. Researchers had asked the labs to match a series of DNA samples. They knew which ones were from the same person, but found that in over 1 per cent of cases the labs falsely matched samples, or failed to notice a match. The statisticians then calculated that a substantial human error had occured in 12 in every 1,000 tests.

British forensic experts expressed alarm at the errors and stressed they were more numerous than expected.