something bad would happen. >> we just seayed a bunch of lives. there is no doubt about it. >> reporter: police started investigating 26-year-old when li sun this year after he made unusual statements to a school official. they flagged to it the atf and found out he owned an assault-style rifle and ammunition. when a detective referred to him, sun referred to his weapon as a sniper rifle, but said he never thought about hurting himself or others. days after that interview, sun bought a second assault-style rifle this one with a bipod and scope. official says he owned both guns legally. >> we know if one individual falls through the cracks, very bad things can happen. >> reporter: but then his visa was revoked due to an issue related to gun issues. he stopped going to class. >> i think there was a disaster about to happen and we stopped it. >> reporter: sun is held by immigration officials and is expected to be deported soon. and he will not be allowed to return to the u.s. for ten years. victor blackwell, cnn, atlanta.