University Police shifted its focus off campus, to the north side home of Nathaniel Brown, ONN Affiliate WBNS reported.

Brown's home on Grasmere Avenue was searched, WBNS reported.

WEB EXTRAS:  Ohio State Police News Conference Video   | Images From Scene
E-Mails:  From OSU President Gee | From OSU Emergency Management

"We're going to start piecing together the items we found here that might help us," University Police Lt. Rick Green said.

Larry Wallington, 48, was killed and Henry Butler, 60, was injured.

"Something like this is very tragic, there had to be something that precipitated this and we're going to try to find out," Green said.

Brown was facing foreclosure on his house and had been notified he was going to be fired from his custodial job on Saturday, WBNS reported.

Records show Brown received an unsatisfactory performance review and Wallington was one of his supervisors.

"Hindsight is always going to be 20/20," Green said. "When you step back and look at something, well you go back in time and say 'Well, now that makes sense,' but at the time it didn't. By doing the investigation that we're doing, it could certainly help a lot people."

OSU President Gordon Gee held a news conference Wednesday, calling the shootings and Wallington's death a "tremendous loss for the university."

"I want Mrs. Wallington to understand this is not just simply her family, or the immediate people he worked with, it's a loss for all of us," Gee said. 

Gee said the university will re-examine how employees are hired and evaluated.

"What we've have done has generally worked very well," Gee said. "What we now have learned is the fact that there are some things that we need to take a look at, and that's precisely the things we'll take a look at."

Since Tuesday's shooting, thousands more students had signed up to receive Buckeye Alerts, the university's emergency alert system.

The system notified more than 26,000 people who had signed up to receive alerts, Hogan reported.

Brown was incarcerated in the late 1970s for receiving stolen property, but a background check done by OSU turned up nothing, because of how old the offense was, Hogan reported.

Brown lied on his job application, not putting a checkmark in the box for felony convictions, Hogan reported.

Butler was taken to The Ohio State University Medical Center after the shooting.  It was not immediately known when he would be released.

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More Information:

• Buckeye Alert System

Previous Stories:  

March 10, 2010: Ohio State Shooting Victim Could Leave Hospital Today
March 9, 2010: OSU Gunman Was Being Fired
March 9, 2010: Ohio State Univ. Worker Shoots 2, Kills Self Inside Campus Building
March 9, 2010: Second Person Dies In Ohio State Campus Shooting

©2010 By ONN. WBNS-TV in Columbus contributed to this report.