Few types of crime are as shocking—and polarizing—as filicide, in which a parent kills one or more of his or her children. Some people cannot imagine a penalty severe enough for a parent who would commit such a horrendous act. Others find it so incomprehensible that they have no doubt that the parent was insane at the time and should not be sentenced to a long prison term or death.

One of the country’s leading experts on filicide, forensic psychiatrist Phillip Resnick, M.D., has developed a classification for this type of killing based on the parent’s motive. Resnick described the various types of filicide in his classification and the likelihood of a successful insanity defense in each at the October annual meeting of the American Academy of Psychiatry and the Law in Newport Beach, Calif.

Resnick has served as an expert witness is several high-profile filicide cases, including that of Andrea Yates, who in June 2001 killed her five children.

Resnick defines five types of filicide. In "altruistic" filicide a parent—almost always a mother in this category—kills her child or children as an extension of a suicide attempt. "These mothers see their children as an extension of themselves," he said. "They do not want to leave a child motherless in a ‘cruel’ world as seen through their depressed eyes."

In a second type of altruistic filicide a child is killed to end his or her real or imagined suffering. "These mothers may project their own unacceptable symptoms onto the child," he said.

In "acutely psychotic" filicide, hallucinations, epilepsy, or delirium drive a parent to kill a child. Psychiatrist evaluators will not find a "comprehensible motive" in this type of killing, Resnick said.

His third category involves "unwanted child" filicide, which includes homicides in which a parent no longer wants the child.

"Fatal maltreatment" filicides fall into two types, he suggested. In one—the most common motive for child homicides in the United States—children die as the result of a beating, and homicide was not the goal. The other type, which is extremely rare, he noted, occurs as the result of Munchausen syndrome by proxy.

Resnick’s final filicide motivation is "spouse revenge." This category includes cases in which parents kill their children to make their spouse suffer, most often in revenge for infidelity.

While states impose a variety of tests and principles to their insanity defense standards—which can include the ability to know that an act violates the law, the ability to refrain from committing the act, or the belief that the act was morally justified, for example—in a jury’s eyes certain evidence mitigates the act or points strongly to its wrongfulness, Resnick noted. Efforts to avoid detection or dispose of evidence could indicate that the person recognized that the act violated the law, as would taking steps to avoid detection or, in contrast, notifying the police that a crime was committed.

Juries will have to evaluate such factors in determining whether the person has or had a mental illness that meets the state’s insanity standard, he said.

In the subset of altruistic filicide in which the killing is actually an extended suicide attempt, severe depression may have distorted thinking "so that the mother believes her children will be better off in heaven with her," Resnick said. This is similar to the explanation that Andrea Yates gave for murdering her children. (Resnick was an expert witness for the defense in that case.)

"In these cases, it is usually clear that the mother knows the nature and quality of her act and that killing is legally wrong. However, the mother often believes she is doing what is morally right for her child," he said.

In altruistic filicide cases, the success of an insanity plea hinges in large part on whether the insanity standard uses the word "appreciate" or "know" to characterize the parent’s understanding of the wrongfulness of the killing.

In altruistic filicide to relieve suffering, juries would likely view the act as euthanasia, which does not derive from a mental illness, and find the parent unqualified for an insanity defense, Resnick suggested.

In the category of acutely psychotic filicide, "the parent may not know the nature and quality of the act," he explained, if it occurs during an epileptic seizure or delirium. In assessing a person who appears to fall into this category, evaluators "must always consider malingering," he stated. Command hallucinations, such as obeying orders to kill from God or Satan, are included here, and the issue of whether a parent could have refrained from the killing may be the point on which an insanity defense hinges, Resnick said.

Parents whose children die as the result of beating have little claim to a major mental disease, with the rare exception of a mother "who is so depressed she neglects the care of the child," he noted. "Nonetheless, an insanity defense based on postpartum depression is not often successful in the United States."

There is even less basis for an insanity defense in unwanted-child filicide, a category that also covers most neonaticide cases, which Resnick defined as killing a baby less than one day old. There is almost no chance that jurors will see grounds for an insanity defense when filicide is rooted in spouse revenge. ▪