Police and the FBI are looking into the lives of the two gunmen who died in the weekend assault. One suspect mother said the violence was not like him.
Police say 30-year-old Elton Simpson and 34-year-old Nadir Soofi drove up and began firing outside the Curtis Culwell Center in Garland just as a controversial Prophet Muhammad art event was coming to an end.
The roommates from Phoenix, Ariz. were both fatally shot by police.
Soofi was born in Dallas at Presbyterian Hospital and lived in Garland with his family until he was 3. His mother, Sharon Soofi, told FOX 4 that her son was not a violent man and has an 8-year-old son.
She said he was running a carpet cleaning business with Simpson. She believes her son was influenced by Simpson's radical beliefs.
Sharon Soofi found out about the Garland incident Monday morning from her other son, who lives in Phoenix with the pair. She now lives an hour outside Houston.
Soofi was raised Muslim and was very involved in his local mosque, his mother said.
Sharon Soofi spoke to her son two weeks ago and said nothing seemed out of the ordinary.
"I never heard my son mention ISIS," she said. "This Elton guy, I don't know what his mindset was. I do think he had a lot of influence over my son for some reason and that he was the one that came up with this idea to go to Garland and do this horrible thing."
According to Soofi's family, none of them knew of any planned attack.
"I'm numb, I'm just numb..." Sharon Soofi said. "I haven't an idea how he could come to do something like this."
Soofi's younger brother saw the pair leave Friday night in his car and didn't hear anything until he saw the news reports mentioning Simpson.
A lawyer who previously represented Simpson said he was a devout Muslim and respectful of the legal process. Arizona lawyer Kristina Sitton represented Simpson, who according to court documents was convicted in Phoenix of lying to the FBI in 2010, about whether he'd discussed traveling to Somalia.
Sitton said she felt the charges were "completely trumped up," to justify the costly investigation. She said he had converted to Islam as a young man.
A search of federal court records did not reveal any criminal cases brought against Soofi.
A resident of a Phoenix apartment complex said Soofi and Simpson, who lived in the unit being searched on Monday, largely kept to themselves but that one was friendly on occasion.
Bob Kieckhaver was among the residents of the Autumn Court Apartments who were evacuated for about nine hours on Monday from units near the one being searched.
Kieckhaver said one of the men, who had a beard and wore a Muslim prayer cap, spent time working on a black Chevy that was up for sale about two months ago. Kieckhaver said that man was quiet, while the second man who lived in the apartment would greet other residents at the mailbox. He said both men would feed stray cats on a patio.
A mosque president in Phoenix said Simpson had worshipped at the Islamic Community Center of Phoenix for about a decade. But Usama Shami said Simpson quit showing up over the last two or three months.
Shami said Simpson got along with everyone at the mosque. But Shami said Simpson was rattled by an FBI investigation driven by an undercover informant who infiltrated the mosque.
Investigators have not revealed if the pair had ties any terrorist groups, but court documents show Simpson was investigated in 2006 for his association with a suspect the FBI believed to be setting up a terrorist cell in Arizona.
He received three years of probation after his arrest in 2010.
The Associated Press contributed to this report.
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