Elton Simpson, one of two gunmen shot dead at an event in the Dallas suburb of Garland exhibiting cartoons of the Prophet Muhammad had been a terror suspect, court documents show.
He had been under surveillance since 2006 and was convicted in 2010 for lying about plans to go to Somalia, the files reveal.
Elton Simpson had shared a flat in Phoenix, Arizona, with the person named by authorities as the other gunman, Nadir Soofi.
Both were shot after opening fire at a conference centre near Dallas.
Elton Simpson’s family has said that there was no sign he was planning to carry out such an attack.
The statement, made on behalf of unnamed family members, said his relatives were “heartbroken and in a state of deep shock”.
On May 4, FBI agents searched Elton Simpson and Nadir Soofi’s home in Phoenix and a white van parked outside.
According to Arizona court documents, Elton Simpson was charged in 2010 with lying to FBI agents about planning to go to Somalia to engage in violent jihad, or holy war.
A judge found Elton Simpson guilty of making a false statement and he was sentenced to three years’ probation and a $600 fine.
The judge ruled there was insufficient evidence that the false statement involved international terrorism.
The court document also showed that Elton Simpson had been under investigation since 2006 because of his association with an individual the FBI believed was trying to set up a terrorist cell in Arizona.
Elton Simpson had told an informant in 2009 that it was “time to go to Somalia”, adding: “We gonna make it to the battlefield.”
He later said he was planning to travel to South Africa and then on to Somalia.
The incident on May 3rd unfolded when a car drove into the car park of the Curtis Culwell Center in Garland, where a Muhammad Art Exhibit organized by the controversial American Freedom Defense Initiative (AFDI) was being held.
The conference included a contest that offered a $10,000 prize for a cartoon of the Prophet Muhammad. Depictions of the Prophet Muhammad are offensive to many Muslims.