Houston ? Believing that Satan wanted her to drown her five children, Andrea Yates knew killing them was wrong and therefore wasn’t insane as defined by law, a forensic psychiatrist testified Friday during her second murder trial.

Dr. Park Dietz told jurors that he based his opinion about Yates on her acknowledgment that her thoughts were bad and killing the children was a sin.

“She had obsessions about a thing (hurting her children) for years, and at some point concluded that it must be Satan,” he said.

By contrast, a person who commits a crime believing that act was ordered by a “good and infallible” God would be insane, he said.

Dietz’s testimony in Yates’ first trial led an appeals court to overturn her 2002 murder conviction.

He said during that trial that an episode of the “Law & Order” television series that aired before the Yates’ drownings depicted a woman being acquitted by reason of insanity after drowning her children in a tub. A prosecutor had suggested that Yates was inspired by the episode. The appeal pointed out no such episode existed.

Yates, 42, has again pleaded innocent by reason of insanity. She will be sentenced to life in prison if convicted.