Little Brother Smoking?!

Okay, so I believe I found out today that my little 16 year old brother may be smoking, I have some good friends who have mention it, he doesn't smell like smoke, also I found a lighter in his car(what would a 16 year old be doing with a lighter in his car if it weren't for smoking?) I think he keeps his cigarettes in his glove box, but its locked. He's not dumb enough(at-least I think) to keep them in his room.
Should I try to find more evidence of this or Do you think I should tell my mother about this, smoking is pretty looked down upon in my house, smoking in my opinion is dumb anyways. I would rather not confront him myself, because I don't think he'll respect me as much, and I would think he just started so I know its easier to stop now, so what do you think and lately his academics have been dropping he has like a 2.5 gpa now.