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.