In some cases, the mother then kills herself as well, sparing us the conundrum of deciding her guilt. [Andrea Yates] did not. But she fits the classic pattern. Since the birth of her firstborn, Yates had had visions of a knife and blood and child-murder. She twice tried to commit suicide, and had told a psychologist, "I had a fear I would hurt somebody. I thought it better to end my own life and prevent it."

Said Dr. Eileen Starbranch, the psychiatrist who treated one of her postpartum depressions, "She would rank among the five sickest - - and most difficult to get out of psychosis -- people that I've ever treated." And while her psychosis could often be controlled by medications, her doctor had stopped her antipsychotics just weeks before the killings. Even the prosecution psychiatrist admitted that when interviewed the day after the killings, she was "grossly psychotic," telling the county jail psychiatrist that voices had told her to kill her children.

This is not to say that any criminal can rationalize his crime as being for some higher good. This extenuation only applies in the case of severe mental derangement. Andrea Yates was clearly mentally deranged, not as proved by the murders -- that would make the murders self-acquitting -- but as demonstrated by her noncriminal behavior: self-injury, severe withdrawal, bizarre behavior, occasional catatonia, delusion, hallucinations.