And yet on Thursday, the 27-year-old Kazmierczak, armed with three handguns and a brand-new pump-action shotgun he had carried onto campus in a guitar case, stepped from behind a screen on the stage of a lecture hall at Northern Illinois University and opened fire on a geology class. He killed five students before committing suicide.
University Police Chief Donald Grady said, without giving details, that Kazmierczak had become erratic in the past two weeks after he had stopped taking his medication. But that seemed to come as news to many of those who knew him, and the attack itself was positively baffling.
"We had no indications at all this would be the type of person that would engage in such activity," Grady said. He described the gunman as a good student during his time at NIU, and by all accounts a "fairly normal" person.
"There were no red flags," Grady said. "He was someone who was revered by students and teachers."
Just last spring Kazmierczak was a success story, a sociology grad student here who'd earned a Dean's award for a paper on prison society, reports CBS News correspondent Cynthia Bowers.
Exactly what set Kazmierczak off - and why he picked his former university and that particular lecture hall - remained a mystery. Police said they found no suicide note.
Investigators learned that a week ago, on Feb. 8, Kazmierczak walked into a Champaign, gun store and picked up two guns - the Remington shotgun and a Glock 9mm handgun. He bought the two other handguns at the same shop - a High Point .380 on Dec. 30 and a Sig Sauer on Aug. 6.
All four guns were bought legally from a federally licensed firearms dealer, said Thomas Ahern, an agency spokesman. At least one criminal background check was performed. Kazmierczak (pronounced kaz-MUR-chek) had no criminal record.
Authorities responded quickly to the shooting; the first 10 police officers were on the scene in 90 seconds. NIU launched its emergency alert system - a carefully rehearsed plan developed after Virginia Tech - sending out e-mails and messages on Web sites to notify students that a possible gunman was on campus and they needed to find a safe area.
NIU Vice President Eddie Williams says his school learned a valuable lesson from Virginia Tech; still, he believes more drastic changes may be needed, reports CBS News correspondent Randall Pinskton.
One idea being proposed in nine states is allowing licensed gun owners - students or faculty - to carry weapons on campus. But many universities are strongly opposing that idea, saying more guns on campus would only increase the risk of more violence, Pinkston adds.
Kazmierczak had a State Police-issued FOID, or firearms owners identification card, which is required in Illinois to own a gun, authorities said. Such cards are rarely issued to those with recent mental health problems. The application asks: "In the past five years have you been a patient in any medical facility or part of any medical facility used primarily for the care or treatment of persons for mental illness?"
Kazmierczak, who went by Steve, graduated from NIU in 2007 and was a graduate student in sociology there before leaving last year and moving on to the graduate school of social work at the University of Illinois in Champaign, 130 miles away.
Army records indicate he enlisted in Sept 2001 and was discharged in Feb. 2002. He received an "entry level separation" which is neither honorable nor dishonorable, but rather uncharacterized.
"It was absolutely not due to bad conduct. It was an administrative discharge and we don't know why," Maj. Anne Edgecomb told CBS News.