One of the slain Garland shooters has been identified as 30-year-old Elton Simpson of Phoenix, Arizona, a man who was already the subject of a terrorism investigation.

He is believed to be the author of Twitter messages issued prior to the assault on the Mohammed Art Exhibit and Competition under the hashtag #TexasAttack. Federal law enforcement sources are describing him as a “terrorist wannabe,” but it is not yet clear which international terrorist organizations he wanted to be part of.

“Overnight and today FBI agents and a bomb squad were at Simpson’s home in an apartment complex in north Phoenix where a robot is believed to be conducting an initial search of the apartment,” reports ABC News.

Judging by the profile of Simpson presented in the L.A. Timesit sounds like his fanboy enthusiasm for jihad might have been directed towards al-Shabaab, the ultra-violent Somali terror gang currently allied with al-Qaeda, but reportedly entertaining overtures from ISIS.

“Elton Simpson was prosecuted in 2010 in federal court in Phoenix for making false statements to FBI agents about going to Somalia to engage in jihad,” the L.A. Times writes. “He was found guilty of making the false statements, but the judge ruled that there was insufficient evidence to conclude that the crime was directly involved to ‘international terrorism.’ Simpson was placed on 3 years’ probation and fined $600.”

(Incidentally, the Times mentions that the organization hosting the Mohammed Art Exhibit, Pamela Geller’s American Freedom Defense Initiative, has been “classified by the Southern Poverty Law Center as an anti-Muslim hate group.” This is not the first time a group targeted by the SPLC has been violently attacked by individuals armed with something a bit heavier than press releases.)

Simpson was very eager to reach the “battlefield” of Somalia in 2009, based on statements he made to the FBI’s informants. “If you get shot, or you get killed, it’s [heaven] straight away,” he explained to an informant, presumably using an Islamic term such as jannah or firdaws for Paradise, or the level of Paradise reserved for martyrs. “Heaven is what we’re here for… so why not take that route?”

The Dallas Morning News mentions a report that the other Garland shooter, as yet unidentified by police, was Simpson’s roommate.

After reviewing court documents in the case mentioned by the L.A. Times, Heavy.com notes Simpson “was born in Illinois and then moved to Phoenix,” where “he converted to the Muslim religion at a young age.”

This article also notes that ISIS had been using social media to encourage attacks on the Garland event. It is not currently known if Simpson was aware of these messages, although if he is the author of the #TexasAttack Tweets, it is a reasonable possibility. Some ISIS affiliated social media users have claimed responsibility for the attack, and U.S. counter-terrorism authorities had reason to believe an ISIS action on American soil was imminent, but that doesn’t automatically mean Simpson and his accomplice were operating under their command.

The Twitter account suspected of belonging to Simpson used a photo of American-born, drone-eradicated al-Qaeda guru Anwar al-Awlaki. However, the very same Twitter photo claims the user swore bay’ah, which is the ritual oath of allegiance to the head of the Islamic “caliphate.” Al-Qaeda doesn’t claim to have established a caliphate, but ISIS does, with its chief Abu Bakr al-Baghdadi as “caliph.” Islamic State emissaries have been visiting terrorist groups and insurgents from Afghanistan to Libya, demanding they swear bay’ah to al-Baghdadi, with a disturbingly high rate of success.

Update, 1:00 PM EST: Elton Simpson’s father Dunston denounced his son’s actions to ABC News.  “We are Americans and we believe in America. What my son did reflects very badly on my family.”

Dunston Simpson described his son as “always a good kid,” but said he “made a bad choice.”  Father and son had not spoken much recently, “because we had some very serious differences.”

According to his father, Elton Simpson was “on vacation” from his job in a dentist’s office at the time of the shooting, and had been away from the office for a few weeks.

Update, 1:30 PM EST: The second shooter has been identified as Nadir Soofi, 34.  According to law enforcement officials quoted by the Washington Posthe was indeed Elton Simpson’s roommate.