Federal authorities have closed their investigation into the across Austin last year, finding Mark Conditt had no overarching ideological motivation and acted alone.
In a Jan. 10 filing, U.S. Attorney John Bash said law enforcement closed its investigation after finding "no evidence of communications or links between Conditt and any international terror groups or domestic hate groups."
In the early hours of March 21, Conditt detonated an explosive device, killing himself in Round Rock on I-35 after a police pursuit.
Before his death, the 23-year-old claimed responsibility in a video confession for in February and March last year that killed two Austinites � Stephan House and Draylen Mason � and seriously injured others.
News of the investigation's closure was first reported by .