O'Keefe, a retired Carmel police officer, who will serve his sentence at the Putnam County Jail, hit a Jeep on Route 6 and killed the Somers teaching assistant on Nov. 14, 2015, said lohud.com.
As part of a plea deal worked out by the Putnam County District Attorney's Office, O'Keefe also waived his right to appeal, added lohud.com.
The Mahopac resident, 59, was arrested the night of the crash, which occurred at 9:38 p.m. on Route 6. According to the investigation, O'Keefe who was driving a Dodge Caravan was cut off by Anna Estrada in her friend's Jeep, state police said after the crash.
O'Keefe's minivan rammed into the Jeep, which flipped, and hit another vehicle, state police said.
Steven Ghelarducci, the owner of the Jeep, was a passenger along with his wife and Estrada's husband, Ernest Estrada.
Fran Ghelarducci died at the scene, the other passengers of the Jeep were treated at a nearby hospital for non-life threatening injuries.
O'Keefe, who refused to take a Breathalyzer test, was not injured, police said.
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