@cbsnews: As a defense witness in the 2006 retrial of Andrea Yates, the Texas mother who killed her own children to "save them from Satan," Dr. Phillip Resnick testified that severe postpartum psychosis caused Yates' behavior. she was found not guilty by reason of insanity in her case. Today, he took the stand for the defense in Lindsay Clancy's trial and testified that Lindsay "did not have control of her own body" after hearing the command to kill her children. "It was almost like she was a puppet and someone else was pulling the strings," he said. The prosecution, however, called their own expert witness, Dr. Avram Mack, who said Clancy "was suffering a major depressive episode."