BOSTON (AP) — The former University of Alabama professor sentenced to life in prison last week in a shooting rampage that killed three of her colleagues wants to go on trial in the 1986 death of her brother in Massachusetts.

Court documents filed by Amy Bishop’s lawyer say she objects to a decision by Norfolk District Attorney Michael Morrissey to decline to prosecute her in the killing of 18-year-old Seth Bishop.

Attorney Larry Tipton says Bishop wants to prove at trial that she had a “loving and caring relationship” with her brother and that the shooting was accidental.

Morrissey said last week that he decided not to move forward because she has already received life sentence in the Alabama killings.

Bishop claims she accidentally shot her brother while trying to unload her father’s shotgun in the family’s Braintree home.

Copyright 2012 The Associated Press.