DEKALB, Ill. &

The gunman who killed himself and five students at Northern Illinois University on Thursday was an award-winning graduate student, described by professors as friendly and respectful.




Stephen Kazmierczak, 27, donned a dark coat and black ski cap before he began firing into a crowded lecture hall. But that was an image in sharp contrast to the well-adjusted man who was attending the University of Illinois at Urbana-Champaign.




"He looked like every other middle-class, clean-cut college kid," said Christopher Larrison, a professor of social work who hired Kazmierczak last fall to help record data for a research project. "He was a personable young man, very earnest."




But Kazmierczak's life also appeared to be turbulent. According to police and people who knew him, he bounced around in side jobs and had stopped taking medication that left his behavior "erratic." He also might have been involved in a romantic relationship that recently ended.




Kazmierczak quit his job with Larrison not long after he was hired. He bought one gun in December and two in February, all purchased legally, that he carried during the rampage, police said. After attending NIU as an undergraduate, where he won a dean's award, Kazmierczak last year was accepted into the school of social work at the University of Illinois.




His days at the Urbana-Champaign campus appeared to be going well. He was earning good grades and his graduate adviser, Janet Carter-Black, described him as engaging and flexible.




However, acquaintances told police that Kazmierczak's behavior appeared to change when he stopped taking his medication at some point before the shooting.




That was not the only change Kazmierczak made in the past few months.




He began working 10 to 20 hours a week for Larrison in September, earning about $12 an hour. "His work was very good," Larrison said. "He seemed like a very solid person."




But Kazmierczak quit a few weeks later, when he got a job as a prison guard at Rockville Correctional Facility in western Indiana.




Acquaintances said Kazmierczak wanted a career in the prison system, and the job seemed like a good match with his studies. But he quit before he finished training, working only from Sept. 24 to Oct. 9, said Indiana Department of Corrections spokesman Doug Garrison.




After he left, Kazmierczak went back to work for Larrison, once again entering data from surveys. He quit again a few weeks later.




"I asked him if he needed the money, but he said he didn't," Larrison recalled.




Faculty members at the University of Illinois and NIU said Friday that they were stunned by Kazmierczak's rampage and their own failure to recognize any tell-tale signs of a troubled individual.




"There was nothing on the surface that I saw that was indicative of the kind of behavior we saw," Larrison said. "I was astounded when I learned what happened. It was like being hit by a meteorite."




NIU professor Charles Cappell said Kazmierczak was one of the stars of his sociology classes in the fall of 2005 who helped fellow students through the material. Cappell recruited him to work as a tutor for three semesters at the research laboratory he runs and later wrote Kazmierczak a letter of recommendation.




"He was searching for what his calling was going to be," Cappell said. "The last I heard from Steve was in an e-mail in September. He was upbeat about the program, but that he missed all of us in the lab."




On Friday, Cappell and nearly two dozen graduate students &

many of whom knew Kazmierczak &

gathered at the lab with grief counselors.




"We're feeling lost, anguish, anger," Cappell said. "This wasn't the Stephen we knew."




Police reportedly were looking for a woman who Kazmierczak might have had a relationship with, according to several news organizations. But NIU campus police chief Donald Grady said at a news conference Friday that the shooting spree was not the result of a breakup or failed love affair.




Kazmierczak drove a white Honda Civic to the DeKalb campus and parked it in a lot near the Cole Hall shooting site. He walked up a snowy path, entered the building and then kicked in an exit door to enter the lecture hall, Grady said.




Police investigators said Friday that they found 48 shell casings from handguns and six shotgun shells on the stage in the bloodied NIU lecture hall. Kazmierczak carried a Remington 12-gauge shotgun, which he had hidden in a guitar case, together with three automatic pistols.




On Friday, hundreds of grieving students and red-eyed DeKalb residents &

many clad in the school colors of red and black &

silently streamed up the snowy walkway leading to the Christ the Teacher University Parish for a noon Mass and community vigil.




"I still can't think about it without re-living it, and that's horrible," said George Gaynor, 23, a senior who was in the lecture hall when Kazmierczak opened fire. "I haven't slept. I'm feeling so much, it's overwhelming. I'm just exhausted."




The victims were identified as Ryanne Mace, 19, of Carpentersville, Ill., a psychology major who left a Valentine's Day wish to friends on her web page; Catalina Garcia, 20, of Cicero, Ill., who dreamed of becoming a teacher; Gayle Dubowski, 20, of Carol Stream, Ill., who had a penchant for musical theater; Daniel Parmenter, 20, of Westchester, Ill., a rugby player who helped fraternity brothers organize bingo games at nursing homes; and Julianna Gehant, 32, who spent 12 years with the Army Corps of Engineers, building schools in Laos and barracks in Bosnia.




The science class at Cole Hall was an elective Gehant had taken for fun, said friend Josh Becvar, a fellow member of the NIU Veterans Club.




"It's not ever going to make sense to me," Becvar said. "She served her country overseas. But she died here in a classroom."




Huffstutter reported from DeKalb and Vartabedian from Los Angeles.