ROSEDALE, Md. (WJZ) — Investigators are trying to figure out why a University of Maryland graduate student shot his housemates.

Adam May has more information about the suspected shooter.

People have been coming and going from suspected shooter Dayvon Green’s family’s home in Rosedale all day. Everyone is trying to make sense of the violence.

Disbelief on Golden Ring Court in Rosedale. Neighbors were shocked to hear police say the smart kid from their hometown shot his College Park roommates.

Click here to learn more about the murder/suicide.

“I’m very sad for them. They’re a very nice family,” said a neighbor.

WJZ has learned Dayvon Green was one of NASA’s top interns. An Internet biography states he was interested in robotic sciences. Green recently graduated from Morgan State University and was pursuing his master’s at College Park.

Green’s family declined to comment but told police critical information.

“Detectives learned that the shooter had been suffering from a mental illness. The family let our detectives know that this suspect had had this condition for at least a year and that in the past, he had been prescribed medication for this mental illness,” said police.

Like police, many neighbors want to know where Green got the guns.

“It’s all you hear. Every morning when you turn on the news, someone at school getting shot,” said a neighbor. “It’s a shock to me. It really is.”

State police say Green bought the 9-mm gun legally at a gun shop in Baltimore County in April 2012. But he was not the registered owner of the semi-automatic found in his possession.

A few years ago, Green was selected by managers at NASA for their Elite Ambassador program.