Brown spent five years in prison in the 1970s and '80s for receiving stolen property but lied about it on his job application, records show. It wasn't immediately clear whether Ohio State had done a background check on him.
Ohio State released documents from Brown's personnel file showing that supervisors complained he was tardy, slept on the job and had problems following instructions. The university sent him a letter March 2 informing him that his employment was to end Saturday.
About a half-dozen other employees were in the building when the shooting began, Denton said. He described the shooting as work-related but didn't describe a motive.
The shooting was reported at 3:30 a.m. Tuesday. Police tactical units surrounded the building and found Brown with a self-inflicted gunshot wound in a garage bay, Denton said. He was pronounced dead at a campus hospital several hours later.
Brown had been scheduled to work his normal third shift, Denton said.
One of the victims, building services manager Larry Wallington, 48, died at the scene. The other, operations shift leader Henry Butler, 60, was in stable condition at Ohio State University Medical Center, officials said.
Butler wrote a letter Feb. 11 recommending that Brown be terminated, according records released by the university. Even though colleagues had made a special effort to help Brown, he was not improving, the letter said.
Denton declined to say whether other employees were targeted.
Police also didn't describe the contents of Brown's backpack.
The other employees in the building at the time have been offered grief counseling, Denton said.
"This is a tragic event, and our hearts go out to all of the families," said Vernon Baisden, assistant vice president for public safety.
Police released two 911 calls. In one, a caller tells the dispatcher that he pulled into the garage and heard gunshots. He identifies Brown as the shooter and says Brown was in the process of being fired.
Brown, who was still on probation as a recent hire, had recently complained to a union representative that his supervisors were being unfair in their evaluation of him, said Richard Murray, president of Communications Workers of America Local 4501, which represents custodial workers at Ohio State.
"He was frustrated and upset, certainly. But he didn't make any threats or anything," Murray said. The union couldn't do more with the case because Brown didn't file a formal complaint, he said.
Brown was released from prison in 1984 after serving about five years on a charge of receiving stolen property, records show.
Messages seeking additional information were left with a state prisons spokeswoman.
On his job application, he checked "no" when asked if he had ever been convicted of a felony or misdemeanor. Ohio State's policy on background checks depends on the type of job position, Baisden said.
Both shooting victims had worked for the university for about 10 years. Family members reached Tuesday declined to comment.
Classes went on as scheduled Tuesday. More than 55,000 students attend the main campus in Columbus. The maintenance building is next to a power plant and across the street from Ohio Stadium, home to the university's football team.