Professor Linked to Brother’s Decades-Old Murder After Carrying Out Massacre at Alabama School (FPD CASE VAULT)

Denied tenure and about to lose her job, Harvard-educated neuroscientist Amy Bishop sat quietly through the first 40 to 50 minutes of a routine University of Alabama in Huntsville biology department faculty meeting.

Then she suddenly whipped out a pistol and started blasting away.

By the time her 9 mm handgun jammed that day, Feb 12, 2010, department head Gopi Podila and two professors, Maria Davis and Adriel Johnson Sr., were dead and three others were wounded. Shortly after her arrest, Bishop told stunned cops: "It didn't happen." But later she came to her senses.

The then-45-year-old professor pleaded guilty in September 2012 to avoid the death penalty and wound up with a life sentence.

But Bishop had a chilling past that began when she was 21. On Dec. 6, 1986, she blasted her 18-year-old brother Seth with a 12-gauge shotgun. At the time, authorities ruled it an accidental shooting based on statements by Bishop and her mother.

Then, in 1993, Bishop was questioned about pipe bombs that were sent to her Boston Children's Hospital supervisor, Harvard professor Dr. Paul Rosenberg. He was unharmed, and Bishop wasn't prosecuted.

Never miss a story — sign up for the Front Page Detectives newsletter. Be on the scene the moment news breaks.

Bishop was also charged with assault in 2002 for punching a woman in the head at an International House of Pancakes in Peabody, Mass. But, again, she wasn't prosecuted.

After the Huntsville massacre, she was indicted in her brother's killing, but the district attorney decided not to prosecute because she was already locked up for life.