Steven Kazmierczak, the man who walked silently into a classroom Thursday and opened fire, was not seen as struggling in college. He was not an outcast. And until recently, at least, he was not brooding.
In stark, puzzling contrast to the usual image of a rampaging gunman, Kazmierczak, 27, was described Friday as a successful student - "revered" by his professors. He had been a teaching assistant at Northern Illinois University, the campus to which he returned Thursday, killing five students and injuring 16 others.
The only hint of trouble from Kazmierczak, who had what looked like a bright future in the criminal justice field, had come in the last few weeks, officials said. Family members told them he had stopped taking medication.
Authorities would not say what the medication was for but said that he had grown erratic, according to his family, in the days after he quit taking the drugs.
"We had no indications at all this would be the type of person that would engage in such activity," said Donald Grady, the university police chief. "He was an outstanding student, revered by faculty and staff."
Kazmierczak, who had switched to a graduate school at the University of Illinois, fatally shot himself moments after barraging a large class with rounds from some of his four guns.
He bought his weapons legally from a Champaign gun dealer, officials said. He also bought some accessories from a popular Internet dealer who sold a gun to the assailant in the Virginia Tech massacre last year.
Exactly what set him off - and why he picked his former university and that particular lecture hall - remained a mystery. Police said they found no suicide note.
Authorities were searching for a woman who police believe may have been his girlfriend. According to a law enforcement official who spoke on condition of anonymity to the Associated Press because the case is still under investigation, authorities were looking into whether he and the woman recently broke up.
Kazmierczak grew up in the suburbs of Chicago with a sister and parents who retired to Lakeland in recent years.
His distraught father did not provide any clues publicly. "Please leave me alone. ... This is a very hard time for me," said Robert Kazmierczak, 66, throwing his arms up and weeping after emerging briefly from his house. The shooter's mother, Gail, died in Lakeland in September 2006.
The Polk County Sheriff's Office said it was asked to gather information about the last time he spoke to his son.
A neighbor of Robert Kazmierczak, who lives just north of the Schalamar Creek Golf Club, said Friday said she didn't know him. She was puzzled why three TV news trucks were parked across from his house until a reporter explained. "That's terrible," said Ernestine Walker.
But in Champaign, neighbors of a modest apartment Kazmierczak had moved into not long ago said they sensed that something was not quite right. The look on his face suggested he had "a lot on his mind," said Martha Shinall, 78, who lived across from his apartment, where he sometimes blared his music.
At the Champaign home of his sister, Susan, a message was taped to the door offering sympathies to the victims. "We are grieving his loss as well as the loss of life resulting from his actions."
Information from the New York Times, Associated Press and Times staff writer Michael VanSickler was used in this report.