"At that point I thought, 'OK, whatever's happened, she's fine,'" he said.
Because he was on the scene, he was taken to the police station, where he waited for hours for news.
"And they brought me out and flat out said, 'Your wife's been involved in a shooting,'" he said, recalling that he started shaking at those words.
As he learned the details of the incident, his mind recoiled.
"It's just incomprehensible," he said.
His wife fit the profile of academics, he said. The 44-year-old was "focused, driven, determined."
Some would say she was too driven; others described her as a little weird, and some neighbors have said she had problems controlling her anger.
She fatally shot her brother, Seth, in 1986. Police in Braintree, Mass., declared the shooting an accident, and she was never charged.
But records show Amy Bishop was armed with a shotgun and crouching behind a car when she was taken into custody.
"I drew my service revolver and yelled three times drop the rifle," Officer Timothy Murphy wrote in his report. "After the third time she did."
The incident provided probable cause to file weapons and assault charges against her at the time, police said, according to The Associated Press, but charges were not filed and the statute of limitations has expired.
Bishop was also questioned, and again never charged, in a 1993 attempted mail bombing of a Harvard professor.
In 2002, Bishop admitted in court to punching a mother in the head after the woman was given the last booster seat in an International House of Pancakes restaurant in Peabody, Mass., the AP reported.
Bishop apparently wanted a booster seat for her own young child and yelled at the woman, "I am Dr. Amy Bishop," according to the police report.
Peabody police Capt. Dennis Bonaiuto said Bishop admitted to the assault in court and the case was adjudicated, meaning the charges eventually were dismissed.
Anderson says the IHOP incident was blown out of proportion.
In 2009, dozens of Bishop's students signed a petition to remove her after appeals to school administrators failed to get her out of the classroom.
One of the letters was addressed to the biology department chairman, Gopi K. Podila, but in a subsequent meeting with the students Podila dismissed their complaints, student Caitlin Phillips told The Associated Press. Podila was the first person shot when Bishop began her alleged shooting spree. Maria Ragland Davis and Adriel Johnson also were killed.
In at least three complaints to administrators, the students said Bishop had unsettling ways, never looked students in the eye and frequently talked about her alma mater, Harvard University.
"We could tell something was off, that she was not like other teachers," Phillips told the AP.
ABC News' Michael S. James and Susan Donaldson James contributed to this report.