Elton Simpson, shooter in Texas prophet cartoon contest, from Illinois

GARLAND, Texas (WLS) -- The ABC7 I-Team has learned one of the shooters in Garland Texas in response to a Prophet Muhammad cartoon contest, is originally from Illinois.

Elton Simpson was born in Illinois and converted to Islam at a young age and moved to Arizona with his parents, the I-Team reports. The I-Team is investigating previous addresses in Westmont, Downers Grove and Chicago.

DOCUMENT: Statement from Simpson family of Phoenix

Federal law enforcement officers consider the attack in Texas Sunday to be a two-man personal jihad. Roommates who lived in Phoenix went to a suburb of Dallas to attack an event they considered anti-Muslim. Both were killed in a shootout with local police. Now, the I-Team has learned that one of the jihadists, Elton Simpson, was born in Illinois and grew up in suburban Westmont, apparently before being radicalized in Arizona.

At 6:45 p.m. Sunday, gunshots rang out at a Garland, Texas, community center.

"They drove up got out and opened fire on the security officer," said Garland police spokesperson Joe Harn.

At 7:10 p.m., during live streaming of them Mohammed event, the 300 attendees were taken to safety.

The pair of gunmen, dressed in body armor, wounded a security guard before an off-duty policeman killed both attackers.

Investigators identified one of the shooters as Nadir Soofi, 34, a University of Utah graduate who had been living in Phoenix with Elton Simpson, 30.

Prior to moving to Phoenix, Simpson lived with his parents in an apartment complex in Westmont.

Westmont police say he had no criminal record in the town; their only record of him was in 1996 as the victim of a theft.

As federal agents swarm the apartment Simpson more recently shared with Soofi, investigators say they believe both men were radicalized in Phoenix. Simpson attended Washington High School where, his attorney says, he converted to Islam. Not long after, according to the FBI, Simpson was in touch with a man trying to start a terror cell in Phoenix, a native of Kenya named Dabla Deng. Deng was eventually paid by federal agents to wear a body wire, engaging Simpson in a plot to commit violent jihad.

"He just felt that he was being targeted because of his religious beliefs and I kind of believed the same," said Kristina Sitton, Simpson's attorney in 2010.

Simpson was convicted for lying to federal agents about that plot. According to court records, Simpson talked about "the obligation to fight jihad overseas" in conversations the FBI taped.

Authorities believe Simpson was also behind twitter messages sent shortly before Sunday's armed assault, messages that included the hashtag "#texasattack."

Elton's father, Dunston Simpson, tells the ABC7 I-Team that his son made a bad choice in what he did Sunday. Dunston says that his family is American and they believe in America, and that what his son did reflects very badly on his family.