A hundred pieces of evidence, no motive

As new details continue to surface, FBI agents are analyzing reams of evidence to uncover a profile and motive for the Northern Illinois University gunman.

"If there is a motive out there to be found, I'm confident (investigators) will find it," said NIU Police Chief Donald Grady Wednesday, nearly a week after the campus carnage on Valentine's Day.

FBI agents are collecting notes from 120 interviews and more than 100 pieces of evidence culled from the bullet-riddled NIU lecture hall as well as the shooter's hotel room, car and Champaign apartment.

The information will be analyzed by investigators at the FBI labs in Quantico, Va., said agent Bill Monroe.

A full criminal profile won't be complete for several more weeks, he said. A motive could remain a mystery.

Steven Kazmierczak -- a 27-year-old former NIU graduate student with a history of mental health issues -- apparently tried to leave behind few clues to explain why he would walk into a lecture hall full of students and open fire, killing five and wounding 16, and then turn the gun on himself.

The hard drive to his laptop and computer chip to his cell phone are missing, Grady said. In the weeks before the shooting, the gunman also started hiding the computer from his live-in girlfriend.

"He was secretive with his computer," Jessica Baty, 28, of Wonder Lake told CNN. "When he would sit on the couch with his laptop, he would turn it away from me so I couldn't see what he was looking at."

Baty also revealed that her boyfriend was on three medications: Xanax, for anxiety, Prozac, for depression, and Ambien, for insomnia.

The shooter stopped taking Prozac about three weeks before the shootings, Baty said. It is not clear if he stopped taking the other drugs as well.

After he quit the medication -- which Grady himself declined to identify -- he started acting oddly, authorities say.

"My information is that he was behaving erratically -- he was angry and more prone to outbursts," Grady said about the last few weeks of the shooter's life.

Baty had previously said her boyfriend was on Prozac but didn't identify the other two drugs until Tuesday. She said he was taking them to help with stress from school and to battle obsessive-compulsive tendencies.

Experts say quitting any of the drugs cold-turkey would not normally cause violent or erratic behavior. But taking Prozac with a bipolar disorder could trigger psychotic behavior in a small percentage of subjects, said Dr. Barry Rabin, medical director of Linden Oaks Hospital, a mental health center in Naperville.

It is not known if the gunman was bipolar, which involves wild mood swings. After he graduated from Elk Grove High School in 1998, his family committed him to a group home for about a year because he was "unruly" and cut himself on purpose.

Baty said her boyfriend started seeing a psychiatrist monthly after the couple moved in June 2007 to Champaign from NIU, where both were graduate students of sociology. She says there was no sign that he was "crazy" or about to kill people.

The two left NIU to enroll in the graduate school of social work at the University of Illinois. The shooter studied mental health issues and criminology. Less than a year before the gunman left NIU, his 58-year-old mother died from Lou Gehrig's disease.

A few months before the rampage, the gunman started stockpiling weapons and covering his body in bizarre tattoos, including one of a clown riding a tricycle through a pool of blood.

Investigators still believe the gunman did not know anyone in the ocean science class he terrorized with three handguns and a shotgun at NIU's Cole Hall. But he does have a connection to the auditorium-style classroom.

It is where he took his first sociology class, a field that fascinated the shooter and led him to start racking up good grades and accolades from professors. He also taught in the classroom as a graduate student in NIU's small sociology department.

Jim Thomas, an NIU emeritus sociology and criminology professor who was close to the shooter, speculates that his former student may have chosen the room because it was close to him emotionally.

"He had a sense of symbolism," Thomas told the Associated Press. "Steve chose to end it where he began it."