NYC Nanny Murder Trial Tests Insanity Defense

Yoselyn Ortega fatally stabbed two young children in her care in 2012. Will the rarely successful insanity defense help her avoid a conviction? The defense worked in New York murder cases only a half-dozen times in a decade.

As the grisly murder trial of a former nanny unfolds in a New York City courtroom, the prosecution and defense agree that in 2012, Yoselyn Ortega fatally stabbed two young children in her care. The fate of the 55-year-old ex-nanny rests on whether the jury believes her insanity defense—one of the most controversial, misunderstood concepts in criminal law, the Wall Street Journal reports. “To put it in lay terms, you would have to either not know what you were doing or not know that it was wrong,” said Charles Ewing, who wrote the book “Insanity: Murder, Madness and the Law,” referring to New York law. “That’s a really hard sell under any circumstances.” Valerie Van Leer-Greenberg, Ortega’s attorney, says “the lack of motive in this case is the hallmark of a mentally-ill offender.” The insanity defense is rarely used and even more rarely succeeds. In New York state, of 5,000 murder cases resolved from 2007 to 2016, six defendants were found not guilty by reason of insanity, says the state’s Division of Criminal Justice Services.

Prosecutors say Ortega was aware of her actions when she committed the acts. Ewing, a professor at University of Buffalo’s School of Law, says an insanity defense trial turns into a battle of the experts, with psychologists offering differing assessments of a defendant’s mental state. Most jurors are loath to agree with the insanity defense. Law Prof. Peter Arenella of the University of Southern California in Los Angeles says, “Their attitude is, ‘A lot of these killers are going to have mental illness, but we can’t acquit all of them.’ ”  Van Leer-Greenberg is expected to call on experts to testify that Ortega’s behavior before the killings resembled that of a mentally-ill person. Prosecutors said Ortega killed the children because of conflicts with their mother about workload issues.