(CNN) -- The biology professor charged in the shooting deaths Friday of three faculty members at the University of Alabama in Huntsville fatally shot her brother more than 23 years ago, police said Saturday.

Amy Bishop Anderson, who was then known as Amy Bishop, was never charged in her brother's death, Braintree, Massachusetts, Police Chief Paul Frazier told reporters. Police records detailing the 1986 incident are missing, and a log of the incident lists it as an accidental shooting, he said.

But the account told by Frazier differs from the one published at the time by a Boston newspaper.

"It is a far different story I believe than what was reported back then," Frazier said. "I cannot tell you what the thought process was behind our releasing her at the time."

A December 8, 1986, article in the Boston Globe states that Anderson asked her mother how to unload a round from a 12-gauge shotgun and accidentally shot her brother while she was handling the weapon. The article cited then-Police Chief John Polio as the source.

However, Frazier said an officer, who was involved in the case and still works for the department, told him that Anderson shot her brother in the chest during an argument. The woman allegedly fired a shot in her bedroom without hitting anyone, then argued with her brother and shot him. She fired yet another round in the home before fleeing, Frazier said.

Police arrested Anderson after she pointed a weapon at a vehicle near the house in an attempt to get the driver to stop, but it drove on, Frazier said.

But during the booking process, Chief Polio called and told the officers to release her, Frazier said.

In a telephone call with CNN, Polio -- now 87 and retired -- denied ever calling in the order. He said detectives had interviewed Anderson and her mother -- Judith Baker, who was a member of the police department's personnel board -- as well as the lead investigator, Capt. Theodore Buker, who has since died.

Buker told him that the shooting appeared accidental and the two men agreed she should be released to her mother, Polio said. A request was then filed with the office of District Attorney Bill Delahunt to conduct an inquiry, but Delahunt never did so, he said.

Delahunt, now a Democratic congressman representing Massachusetts, was in Jerusalem on Saturday and unable to comment on the case, spokesman Mark Forest told CNN.

Polio acknowledged that an argument had occurred during the shooting and said that the other shots, including one fired into the ceiling, did not appear aimed at anyone. He also recalled that Anderson had fled the scene. But, he said, he could not remember what he had told the newspaper in reference to the case or why details, including the argument, were not reported.

Polio rejected as "laughable" any suggestions that the suspect's mother might have influenced their handling of the case.

"There was no cover up," Polio said. "Absolutely no cover up and no missing records. The records were all there when I left. Where they went in the last 22 years and two police chiefs subsequent, I don't know."

Anderson, a Harvard-educated professor, has been charged with capital murder.

Huntsville Police Chief Henry Reyes said Anderson, 45, was attending a faculty meeting on the third floor of the sciences building Friday afternoon when she shot six colleagues, killing three.

Anderson, a professor and researcher at the university, was arrested as she was leaving the building, Reyes told reporters Saturday. He said a 9 mm handgun was recovered from the second floor of the building late Friday.

Anderson is charged with one count of capital murder, a crime that involved two or more intentional deaths and is eligible for the death penalty in Alabama. Madison County District Attorney Rob Broussard said officials were considering other charges, including attempted murder.

University spokesman Ray Garner has identified the dead as Gopi Podila, chairman of the biological sciences department; Maria Davis, associate professor of biology; and Adriel Johnson, associate professor of biology.

The injured were Joseph Leahy, associate professor of biology, in critical condition; Luis Cruz-Vera, assistant professor of biology, in stable condition; and Stephanie Monticello, staff assistant, also in stable condition. They were taken to Huntsville Hospital.

Authorities have not ruled out the possibility of other suspects in connection with the shooting.

Investigators have interviewed Anderson's husband, Jim.

Anderson had been working at the university since 2003 and was up for tenure, Garner said. However, authorities wouldn't discuss possible motives or whether the issue of tenure may have played a role in the shooting.

Garner said the meeting at Shelby Hall was for faculty and staff in the sciences department, but he gave no other details.

The incident occurred shortly before 4 p.m. (5 p.m. ET), and residence halls were locked down 10 minutes later. An alert notifying the campus about the incident was issued at 4:42 p.m. CT.

Pressed on the amount of time that passed before a campus alert was sent notifying students and faculty about the shooting and the lockdown, university police Chief Chuck Gailes said the lag "didn't impact the safety of people on campus and in the building."

He said there is no specific timeframe that dictates how quickly such an alert is issued, but he said it would be an issue officials will look into.

University President David Williams said there would be a prayer service Sunday.

"We are a resilient community, and we know we will come together to overcome these difficult times," he said.

Williams said the campus would open for employees next week but there would be no classes.

Kourtney Lattimore, a 19-year-old sophomore studying nursing, was one of about 100 students who attended the suspect's anatomy class from 10:20 to 11:15 a.m. Friday., when the subject included neurons.

"Nothing seemed to be off at all," she said about her teacher, who wore a pink sweater in class. "We were all shocked, like, all of us just couldn't believe it."

Lattimore said her anatomy class was not the only one affected by Friday's events. Leahy -- who was wounded in the shooting -- taught her infection and immunity class, she said.

Reached at the couple's home, Jim Anderson told CNN that his wife has an attorney whom he would not identify. He described his wife as a good teacher.