The case against an Arizona woman who spent two decades on death row in the murder of her four year old son has been dealt a crushing blow. A judge on Wednesday said a detective does not have to testify at Debra Milke's retrial. Without his testimony on her purported confession, prosecutors cannot use it at her retrial. In other cases, the detective has been accused of lying under oath. If defense attorneys brought that up in the Milke retrial to try to hurt his credibility, he fears he could face prosecution in those cases. Milke was accused of having two men shoot her four-year-old son in 1989. She spent 24-years on death row. An appeals court overturned her conviction in March and she is free on bond pending a 2015 retrial.