A Tasmanian man is in jail after police used blood from a leech to make a DNA match from a 2001 robbery scene.

The Mercury newspaper reports Peter Alec Cannon, 54, pleaded guilty Monday to an aggravated armed robbery committed on September 28, 2001.

Crown prosecutor John Ransom told the Supreme Court that senior constable Nathan Slater had picked up a leech from near a safe at the scene of the crime.

A DNA sample was taken from the blood in the leech by Forensic Science Services Tasmania.

Seven years later when Cannon was charged with a drug crime and a DNA sample was taken from him, police came up with a match.

The court heard that Cannon and another man had robbed Fay Olson of $500 and poked her with sticks.

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