It's easy to point fingers of blame once the unthinkable occurs, but administrators at the University of Alabama at Huntsville should do some serious soul searching in the wake of of the tragic shooting of six school professors by one of their own.

To be fair, no one could have known biology professor Amy Bishop would go on a shooting spree that would leave three teachers dead and three others seriously injured.

But as the investigation in to the slayings proceed, troubling questions about Bishop's violent past and attempts by observers to alert authorities have surfaced.

Killed in Friday's shooting were Gopi K. Podila, the chairman of the Department of Biological Sciences, and professors Adriel Johnson and Maria Ragland Davis.

But Bishop flashed a violent nature before the school shootings.

In 1986, at the age of 19, Bishop shot and killed her younger brother, Seth. Bishop avoided prosecution claiming the gun went off accidentally. Police never fully investigated the shooting, even though Bishop and her mother gave conflicting accounts of what happened, according to published reports.

Bishop was also suspected of sending pipe bombs in the mail to a student adviser, who was critical of her work, when she was a graduate student at Harvard.

And in 2002, Bishop was charged with punching a woman in the head, after demanding that the woman relinquish a child booster seat she was using for her toddler. Bishop received probation, and anger management classes were recommended by prosecutors.

Even her own students sensed something was wrong as recently as last year.

A group of her students took the usual step of presenting a signed petition to campus administrators to complain that Bishop was ineffective in the classroom and acted in odd ways. No action was taken, but Bishop was angry that the university withheld tenure from her.

Family members of the victims have questioned how Bishop was hired in view of her past actions.

"I think they need to do a little more investigation when coming down to hiring teachers and things like that," said Melissa Davis, whose stepmother was Maria Ragland Davis, told reporters Monday. Her sister, Latashia Davis, said she was angry: "How did she even get a job working at the school if she had this type of background?"