Former classmates of the College Park shooter are surprised by the killings.

ROSEDALE, Md. - Dayvon Green, 23, was an honors student, an intern at NASA Goddard, and the one engineering students at Morgan State University wanted on their side for team projects.

"He would have to be going through a lot after leaving Morgan to be pushed to that extent to do such things.  He had to be out of his shell to do that," said Aderojuola Agoro, Green’s former classmate.    

Now there's a different picture of Green.  Police in Prince George's County say he is the gunman who killed one roommate and injured another before killing himself outside of their College Park home.

All three were students at the University of Maryland.  There was more behind the man who friends remember. 

"The family let our detectives know that this suspect who had this condition for at least a year and that in the past he had been prescribed medication for this mental illness," said Julie Parker, spokeswoman, Prince George’s County Police.    

We went to the Rosedale neighborhood where his family lives, but neighbors asked us to stay away from the family.  We don't know Green's exact illness or what medication he was taking.

Police say the 9 mm handgun used in the killing was purchased legally in Baltimore County.  The ATF is looking at the stash of weapons Green owned.

"There was a fully loaded semi-automatic weapon discovered in a long bag.  That bag contained that weapon, multiple rounds of ammunition, a baseball bat and a machete."  

How Green got to the brink may never be known.  He didn't leave a note, describing his thoughts before killing a roommate, injuring another and killing himself.

"It wasn't anything that made him seem like the kind of person that would hurt people.  He wasn't that kind of individual.  He wasn't aggressive.  He didn't have problems with rage," said Agoro.  "You can't force somebody to tell you what's generally wrong with them inside.  You can't," he said.    

The ATF is trying to determine how the shooter bought his guns.  Maryland law states that in some cases a person with mental illness cannot possess a firearm.

A state task force is studying the issue and will recommend changes to the law.