Norfolk District Attorney William Keating announced Wednesday that Amy Bishop had been charged with first-degree murder in the death of her 18-year-old brother, Seth.
Authorities had originally ruled her brother's shooting an accident. But they reopened the case after Bishop was charged in February with gunning down six of her colleagues at the University of Alabama-Huntsville, killing three.
Bishop had told police who investigated her brother's death that she accidentally shot him while trying to unload her father's shotgun in the family's Braintree home.
Those who survived the deadly university shooting rampage back in February said Bishop methodically shot her victims in the head until the gun apparently jammed and she was pushed out of the room.
Associate professor Joseph Ng told The Associated Press he was one of 12 people at a biology department meeting Friday at the University of Alabama-Huntsville. He described the details in an e-mail to a colleague at the University of California-Irvine.
Ng said the meeting had been going on for about half an hour when Amy Bishop "got up suddenly, took out a gun and started shooting at each one of us. She started with the one closest to her and went down the row shooting her targets in the head."
Bishop, a Harvard-educated neurobiologist, was arrested and charged with one count of capital murder and three counts of attempted murder.
Meanwhile, according to Bishop's husband, she went to a shooting range to practice her aim weeks before the campus shooting.
Since the Alabama shooting, revelations about Bishop's past have raised questions about whether much of the violence could have been prevented.
Students at the University of Alabama-Huntsville said they signed a petition and complained to no avail about the classroom conduct of Bishop. The students told The Associated Press they went to administrators at least three times a year ago, complaining that she was ineffective in the classroom and had odd, unsettling ways.
Bishop was denied tenure by the university, and she was vocal among colleagues about her displeasure over being forced to look for work elsewhere.