Harris met Tarnower, a respected cardiologist, in 1965, about two years after her divorce, and they began a 14-year relationship. While he showered the cultivated Jean with gifts and took her on exotic vacations, Tarnower fancied himself as much a ladies' man as he was a doctor, and had other affairs during this period. He ultimately hired a younger woman named Lynne Tryforos to work as a secretary-receptionist at the Scarsdale Medical Center, and they began an affair which lasted several years. It became clear that, much to her distress, Jean Harris was in the process of being replaced by the younger woman.
Harris had been prescribed multiple medications by Tarnower over the years to cope with her demanding role as headmistress of the Madeira School, as well as Tarnower's affair with his secretary.
The mounting tensions of the Harris/Tarnower affair came to a boiling point on March 10, 1980, when Jean drove from the Madeira School in McLean, Virginia to Tarnower's home in Purchase, New York, with a handgun in her possession, with which she said she had planned to commit suicide after talking in person with Tarnower one last time. When she arrived at the house, however, she noticed Lynne Tryforos' lingerie in the bedroom. An argument ensued, and Herman Tarnower allegedly said to her, "Jesus, Jean, you're crazy! Get out of here!" Harris shot Tarnower four times at close range, wounding him mortally. She was arrested and booked for second-degree murder. She pled not guilty, insisting that the shooting was an accident and that the gun had gone off accidentally while he tried to wrestle it away from her.
Harris was released on $40,000 bail raised by her brother and sisters and signed into the United Hospital of Port Chester for psychiatric evaluation and therapy. She then contracted the services of attorney Joel Aurnou to plan her defense.
The case went to trial on November 21, 1980 and lasted 14 weeks, becoming one of the longest in state history. The New York press sensationalized the trial and made Harris a household name from coast to coast. The jury was ultimately unable to believe her testimony and convicted her of second-degree murder.
Many legal experts wondered why Harris did not put forth a defense of "extreme emotional disturbance," which could have resulted in a manslaughter conviction and a much shorter jail term. Harris has always maintained, however, that she had not intentionally killed Tarnower. Joel Aurnou would later state that he gave her other options, but she refused them. Judge Russell R. Leggett ordered her confined to the Bedford Hills Correctional Facility in Westchester County, New York, for the minimum of 15 years to life. Numerous appeals followed the conviction, but the higher courts determined that she had received a fair trial.
Harris’ defence lawyer, Joel Aurnou, was heavily criticised for not sufficiently preparing his client for the trial. The jury wasn’t offered the option of first-degree manslaughter—the mercy option—and the mental health professionals who tested and treated Harris weren’t called to testify.
Eleven years after Harris' conviction (during which she authored three books, taught a parenting class to inmates, and devoted much time to the nursery provided for babies born to inmates) , Governor Mario Cuomo pardoned her on December 29, 1992, as she was being prepped for quadruple bypass heart surgery. Jean Harris was one of very few people to serve less than 12 years in prison for a murder conviction. Upon her release, her plan was to live in a cabin in New Hampshire. She currently lives at the Whitney center, an exclusive retirement center in Hamden, CT.
Harris' murder trial was depicted in the 1981 made-for-television movie, The People vs. Jean Harris. She was portrayed by Ellen Burstyn, who was nominated for an Emmy Award and a Golden Globe Award for the performance. Burstyn would later be nominated for another Emmy Award for a cameo in Mrs. Harris as one of Tarnower's former lovers.
In 2006, a made-for-TV movie depicting Jean Harris's story called Mrs. Harris starred Annette Bening, with Ben Kingsley opposite her as Herman Tarnower. Both Bening and Kingsley received Emmy and Golden Globe nominations for the film.
The 'Scarsdale diet doctor murder' is referred to on the sitcom Seinfeld as the basis for the fictional musical 'Scarsdale Surprise'.