an attempted terrorist attack was foiled. >> reporter: now law enforcement is scrambling to determine if either of the shooters were merely influenced by isis or actually directed to launch the terror attack or something in between. cnn has learned that in recent months, the fbi opened a new investigation into elton simpson. he had already been charged once for lying about trying join jihadists in somalia. less than two weeks before the texas attack simpson directed a message on twitter to this account, believed to belong to an american member of al qaeda in somalia, calling attention to the planned mohamud cartoon event in the dallas suburbs. this hours before the attack simpson urged his twitter followers to follow a known british attacker who one called a significant figure in isis. >> somebody known as a propagandist within isis, somebody known for his hacking skills who has targeted the u.s. military in previous hacks. >> reporter: investigators are exploring whether simpson was working with the isis operative to launch the attack or merely