Enough background is emerging to suggest Kazmierczak was suffering from a mental illness. The sad and scary part of this is that the fear generated by this and other tragedy may contribute to the isolation and stigma of mental illness.

ABC News

"Though Kazmierczak seemed friendly and normal, he had a troubled past. After high school, Kazmierczak's parents sent him to Thresholds-Mary Hill House, a psychiatric treatment center for teens, where he lived for a year while getting therapy and medication for what was described as "unruly" behavior.

Louise Gbadamashi, a former employee at the Chicago treatment center, told the Associated Press that he used to cut himself, and had resisted taking his medications. "He never wanted to identify with being mentally ill," she said. "That was part of the problem."

Apparently in recent weeks Kazmierczak's problems were re-emerging. "We have spoke to people who are close to him and apparently he had been taking medication. He had stopped taking those medications and had become somewhat erratic in the last couple of weeks," said NIU Police Chief, Donald Grady.

The chief declined to specify the type of medication the gunman was on.

In September, 2001, Kazmierczak joined the army. Six months later he was issued an administrative discharge, before he completed basic training, a defense official told ABC News.

Reasons for his exit could 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 as a guard 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.

[..]"Steve was the most gentle, quiet guy in the world. ... He had a passion for helping people," said Jim Thomas, an emeritus professor of sociology and criminology at Northern Illinois who taught Kazmierczak, promoted him to a teacher's aide and became his friend."