LOS ANGELES (AP) – A federal appeals court has overturned a California man’s assault conviction after he went to trial without undergoing a sleep study to bolster his contention that he was sleepwalking.

The 9th U.S. Circuit Court of Appeals said Friday the failure to have Yun Liao undergo a sleep test left his defense weak during his 2003 trial in Los Angeles County. The court cited a subsequent sleep study that determined Liao was a sleepwalker.

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Liao has served his time in prison and is now on parole. The 9th Circuit sent his case back to a lower court with instructions to release him from custody unless prosecutors decide to retry him.

An email to the Los Angeles County District Attorney’s office was not immediately returned.

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Liao was accused of attacking his ex-girlfriend’s son with a hammer.

 

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Copyright 2016 The Associated Press.