Amy Bishop, Ala. professor, pleads guilty to shooting and killing three colleagues in 2010 faculty meeting

(CBS/AP) BIRMINGHAM, Ala. - Amy Bishop, a former University of Alabama at Huntsville professor, pleaded guilty Tuesday to fatally shooting three colleagues and wounding three others during a faculty meeting in 2010, court officials said.

Pictures: Amy Bishop pleads guilty to Ala. Univ. shootings

Bishop, 47, pleaded guilty to one count of capital murder involving two or more people and three counts of attempted murder. She had earlier pleaded not guilty by reason of insanity.

Prosecutors say the former biology professor on Feb. 12, 2010, pulled a gun out of her purse and opened fire at the meeting. Her attorneys say she had mental problems.

Bishop is also charged with killing her brother in Massachusetts in 1986. The shooting of 18-year-old Seth Bishop had been ruled an accident after Amy Bishop told police she shot him in the family's Braintree home as she was trying to unload her father's gun.

But the Alabama slayings led to a new investigation and charges.

In the university shooting, police and people who knew Bishop have described her as being angry over the school's refusal to grant her tenure, a decision that effectively would have ended her employment in the biology department at UAH.

The gunfire killed Bishop's boss, biology department chairman Gopi Padila, plus professors Maria Ragland Davis and Adriel Johnson. Professors Joseph Leahy, staff aide Stephanie Monticciolo and assistant professor Luis Cruz-Vera were shot and wounded.

Prosecutors agreed to recommend a sentence of life without parole for the capital charge, and three life sentences for the attempted murder charges. Sentencing will be after arguments at a hearing on Sept. 24 before Madison County Circuit Judge Alan Mann in Huntsville.

Debra Moriarity was in the faculty meeting at the time of the shooting and is now biology chairman at the school. Prosecutors who met with potential witnesses last Friday said there was a possibility of a plea agreement before the trial began on Sept. 24, she said.

"So I'm not totally surprised by it, but I am surprised it happened this soon," she said.

After Bishop was indicted, prosecutors said Braintree police in 1986 failed to share important evidence, including the fact that Bishop, after she shot her brother in the chest, tried to commandeer a getaway car at gunpoint at a local car dealership, then refused to drop her gun until police officers ordered her to do so repeatedly. Those events were described in Braintree police reports but not in a report written by a state police detective assigned to the district attorney's office.

Moriarity said she was relieved that victims wouldn't have to sit through a trial to see whether jurors convict Bishop.

"I'm glad it's a recognition of the crimes she committed and not trying to get out of something through claiming a mental defect," she said.

Personally, Moriarity said she was relieved that the case is nearly over.

"I had a horrible dream about the trial last night," said Moriarity. Bishop pointed the gun at her and pulled the trigger but it failed to fire.

Moriarity said Leahy, who was shot in the head, returned to teaching a full load of classes and conducting research this fall at the school. The only lingering effects he suffers are reduced eyesight, she said.

"Mentally he is on top of things," she said. "It's an absolute miracle. He's a miracle."

Complete coverage of the Amy Bishop case on Crimesider