Stephen Kazmierczak, the 27-year-old who opened fire on a crowded Northern Illinois University lecture hall, killing five, and then himself on Thursday, was discharged from the United States Army in February 2002 for unknown reasons, ABC News has learned.
Kazmierczak enlisted in September 2001, and was separated before he completed basic training, a defense official told ABC News.
Reasons for his separation include not revealing a condition during initial screening, or not adapting to military life.
The Privacy Act forbids the Army from characterizing the reason for Kazmierczak's discharge.
Kazmierczak had most recently been studying mental health issues at the University of Illinois, and had taken a job at a prison, according to his academic adviser.
But his career as a correction officer at the Rockville County Correctional Facility was short-lived, according to Doug Garrison, a spokesman for the Indiana Department of Correction.
"[Kazmierczak] was employed, starting the 24th of September 2007, as a correction officer at the Rockville Correctional Facility," Garrison told ABCNEWS.com. "He left employment on the 9th of October 2007."
"He just did not come back to work," said Garrison.
The Rockville Correctional Facility is near the Indiana-Illinois border.
"It was very difficult and overwhelming to hear the news," said Jan Carter-Black, an associate professor of sociology, who was both Kazmierczak's professor and adviser at the School of Social Work, at the University of Illinois. "I found Stephen to be a very committed student — extremely respectful of me. I enjoyed having him as a student."
Kazmierczak was a student of Carter-Black's for about a month in the fall of 2007, when he was enrolled in a class called Human Behavior and the Social Environment.
The course, said Carter-Black, focused on the connection between human behavior and the surrounding environment, and met once a week for three-hour sessions. Each class contained around 30 students, and Carter-Black said Kazmierczak always interacted with his peers well during group work, and participated regularly in class discussions.
Toward the end of September, Kazmierczak withdrew from Carter-Black's course to take a job in the prison system, and became a part-time student. In January 2008, Kazmierczak returned to full-time status.
Despite advising him on his courses on mental health issues, Carter-Black said she never noticed anything out of the ordinary about Kazmierczak, and added that he "looked like all the other students."
Earlier reports by NIU campus Police Chief Donald Grady indicated that Kazmierczak's behavior had become erratic in the past few weeks, and it is believed he had stopped taking his medication. The chief declined to specify the type of medication the gunman was on.
Carter-Black said she had no knowledge of Kazmierczak's medical history or treatment.
Kazmierczak had served as a member of the NIU Academic Criminal Justice Association, was a teaching aid during his undergraduate years and in 2006 even received a Dean's Award from the sociology department.
In 2006 Kazmierczak was a co-author of an essay entitled "Self-Injury in Correctional Settings: 'Pathology' of Prisons or of Prisoners," in which an attached biography describes him as having just begun his graduate work at NIU.
Kazmierczak's interests are listed as corrections, political violence and peace and social justice, according to the essay, and he had plans to co-author a manuscript on the role of religion in the formation of early prisons.
In another biography, apparently written by Kazmierczak for the Academic Criminal Justice Association's Web site, he pledged his commitment to social justice and his academic work.
"I've worked very hard as a student," the entry reads.
Kazmierczak worked as the Pirates Cove Children's Theme Park in his hometown in 1995, according to the park's director. He had an acceptable employee record.
On a music site message board from 2006, posters who claimed to be his co-workers wrote, "I remember Steve Kazmierczak … the kind of person who injured kids on the train ride cuz he was mental and he shouldn't be given domain over kids on little faux-traincars with an aluminum baseball bat … "
Originally from Champaign, Ill., Kazmierczak had been a student at NIU in the spring of 2007, where he had majored in sociology. He had been studying at the University of Illinois - Campaign most recently, according to NIU school officials.
Grady said that those who knew him "revered him as an outstanding student" and had no inclination that Kazmierczak was capable of such carnage.
But law enforcement authorities told ABC News that Kazmierczak had likely planned the assault on the school for at least five days — all four guns involved in the NIU shooting were purchased legally from the same Champagne, Ill., gun dealer, ABC News has learned. The Remington shotgun and the Glock 9 mm were purchased Feb. 9, 2008. The Hi Point 380 was purchased Dec. 30, 2007 and the SIG Sauer 9 mm was purchased Aug. 6, 2007 from the same gun dealer.
Authorities were still checking where he obtained two other pistols, a 9 mm Sig Sauer and a Hi Point 380.
He brought the shotgun in a guitar case, police said, and hid the others underneath his jacket.
At approximately 3:15 p.m. Thursday, Kazmierczak — dressed in black and armed with three handguns and a shotgun — entered an introductory geology class and opened fire.
While students ran for cover and hid under their desks, Kazmierczak wounded 16 people, killed five others and then himself.
"The assailant began firing into the assembled class from the stage — from the front," NIU president John Peters told ABC News.
"It didn't seem like he was aiming. He just raised a gun and shot immediately," said Paul Sundstrom, a student who was sitting in the class with his brother Kevin when the gunman opened fire.
With additional reporting by Luis Martinez and Marcus Baram.