Alabama ? The professor accused of killing three colleagues during a faculty meeting is a Harvard-educated neurobiologist, inventor and mother whose life had been marred by a violent episode in her distant past.

More than two decades ago, police said Amy Bishop killed her teenage brother with a shotgun at their Massachusetts home in a shooting that investigators concluded was an accident.

Bishop had just months left teaching at the University of Alabama in Huntsville when police said she opened fire with a handgun Friday in a room filled with a dozen of her colleagues from the school’s biology department.

Bishop, a rare woman suspected in a workplace shooting, was to leave after this semester because she had been denied tenure.