The man behind the shooting in Odessa, Texas, that left seven people dead was not allowed to buy or own firearms after a local court determined he was mentally unfit, The Wall Street Journal reports. Authorities were reportedly still investigating how Seth Aaron Ator was able to obtain the AR-15-style rifle used during the Saturday shooting. One official told the Associated Press that Ator had obtained the gun via a private sale, which allowed him to avoid the background check that previously prevented him from purchasing a gun.

Texas Gov. Greg Abbott confirmed that he failed the background check, and officials told WSJ on Monday that Ator failed because a nationwide criminal background system flagged the mental health decision by the court. The Saturday shooting also injured 22. Ator was killed in a police shootout following the rampage.