By Steve Neavling
The FBI was investigating a Dallas man before he fatally shot his roommate and critically wounded a neighbor and paramedic on Monday.
Derick Lamont Brown, 36, was the subject of an active, open FBI investigation, NBCDFW.com reports. 
Eric Jackson, special agent in charge of the Dallas FBI, confirmed the investigation Tuesday and said his office was reviewing the case file on Brown, who has ties to two black nationalist groups.
The FBI didn’t disclose more information about the open investigation.