Cody Cousins has been identified as the Purdue University student who police say shot and killed senior and undergraduate teaching assistant Andrew Boldt in an incident that rocked the Indiana school’s campus Tuesday.

Police are still piecing together a motive for the killing. Boldt, 21, was killed by Cousins, 23, inside the school’s electrical engineering building, according to authorities. Boldt was set to graduate from Purdue in the spring.

Cousins gave himself up to police after firing four or five shots. Authorities believe Cousins targeted Boldt for murder, but they could not explain why.

“This was not your typical active shooting,” said Purdue Police Chief John Cox, adding that Cousins is not cooperating with police. “It appears to be an isolated and intentional act and not a random shooting.”

Besides his motive, Cousins’ background is also a mystery. The Associated Press reported that it had trouble contacting the 23-year-old’s relatives after the shooting. The news wire service said Cousins had addresses in Warsaw, Ind., and Centerville, Ohio. According to Cincinnati television station WCPO, Cousins attended Springboro High School in Springboro, Ohio, a suburb between Cincinnati and Dayton.

Here’s what else is known about Cousins:

·      He’s no stranger to Purdue police. According to Chicago television station WLS, Cousins had a previous run-in with authorities over an alcohol-related incident. There were no other details about the case.

·      He’s an engineering student at Purdue.

Boldt’s murder came as a shock to the Purdue community.

“Homicides are extremely rare events at Purdue,” Tim Sands, the school’s provost, told WLS. “It’s shocking.”

That shock also extended to Jeff Monday, Boldt’s principal when he attended Marquette High School.

"I can't believe, first of all, that there was a shooting at Purdue and that the victim is one of our graduates. Right now we're just in a state of shock," Monday said.