A biology professor charged with killing three of her colleagues at an Alabama university has been indicted in the 1986 shooting death of her brother in Massachusetts, MyFoxBoston.com.

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.

Bishop was indicted on Wednesday by a grand jury. The case was handed over to the grand jury following a three day inquest in April.

Keating stated that mistakes were made in the original investigation but did not put the blame on a single party.

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.

"Had...evidence been reported to the District Attorney's Office at the time, it would obviously have been presented to a Grand Jury and an indictment for intentional homicide, or murder, could have resulted," said Keating, according to MyFoxBoston.com. This may have saved the life of those three peole in Alabama, he said.

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, Mass., home.

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