PITTSBURGH — The man who shot up a women's aerobics class, killing three people and then himself, was questioned a week earlier by police because he matched the description of a man seen pulling what appeared to be a grenade from a computer bag, authorities said today.

George Sodini, 48, of Scott Township was ultimately let go by Port Authority of Allegheny County police because they couldn't confirm he was the man on the bus July 28, authorities said.

But County police Superintendent Charles Moffatt told a Pittsburgh newspaper that investigators found writings in Sodini's home after the shooting that referenced the situation.

In addition to the shooting deaths, Sodini wounded nine people who were attending the aerobics class at the L.A. Fitness club in Collier Township on Aug. 4.

Port Authority spokesman Jim Ritchie said transit police didn't charge Sodini in the July 28 report because the witness couldn't confirm Sodini was the one with the grenade, and Sodini denied it when police found and questioned him two days later.

"It wasn't until two days later that our sergeant found a guy matching the description," Ritchie said this morning. "There wasn't much more we could do at that point."

The passenger saw a man matching Sodini's description take a grenade out of a computer bag around 7 a.m. July 28 and move it around in his hands. The passenger didn't report it to Port Authority police until that afternoon, Ritchie said, too late for police to search the bus.