A judge has dismissed the murder case against an Arizona woman who spent more than 20 years on death row in the killing of her 4-year-old son.

Judge Rosa Mroz ended the case against Debra Jean Milke on Monday after prosecutors lost their last appeal last week.

Milke was convicted of murder in 1990 in the death of her son, who thought he was going to see Santa Claus at a mall only to be taken to a desert by two men and shot in the head.

An appeals court overturned Milke's conviction in 2013, ruling that prosecutors failed to disclose a detective's history of misconduct. Her conviction was based entirely on a confession Milke gave to the now-discredited detective.