Harvard-educated neuroscientist Amy Bishop, accused of killing three colleagues at the University of Alabama on Friday, was also a suspect in an attempted bombing of a Harvard Medical School professor in 1993.

Bishop and her husband had been questioned by authorities investigating the delivery of a package containing two unexploded pipe bombs to Paul Rosenberg, an associate professor of neurology at Harvard Medical School and doctor at Children’s Hospital Boston. Bishop’s concern that she would not receive a positive evaluation on her doctoral work from Rosenberg and previous violent behavior made her a suspect at the time, according to the Boston Globe.

While Bishop and her husband James Anderson were never charged with attempting to bomb Rosenberg, the incident is one of two recent revelations that tie Bishop to a criminal investigation.

Reports that surfaced after the Feb. 12 shooting revealed Bishop’s involvement in the death of her brother Seth Bishop in 1986.

Bishop, who was 19 years old at the time, shot her brother at least three times before fleeing the scene.

She was later brought into police custody at gunpoint, Braintree Police Chief Paul H. Frazier said at a news conference.

The detailed police report of the 1986 accident, which had logged the shooting as a “sudden death,” has disappeared, Frazier said.

But an investigative report filed several months after the incident has surfaced, leading to rumors of a police cover-up. Former police chiefs in charge of the investigations of the 1986 shooting denied these allegations to several news outlets.

Bishop, a biology professor at the University of Alabama, opened fire during a faculty meeting at the University’s Huntsville campus Friday afternoon. She killed three instructors and wounded three employees. No students were injured.

News sources point out that Bishop had been denied tenure and would have had to leave her position at the end of the academic year—a possible motivation for the shooting.

Bishop completed her undergraduate education at Northeastern University and received a PhD from Harvard in 1993. She became an assistant professor at the University of Alabama in 2003.

—Staff writer Barbara B. DePena can be reached at barbara.b.depena@college.harvard.edu.