Scary Skull Guy Strikes Again!

In the past few weeks, I've documented scary skull guy's contribution to Belltown's general visual squalor here, here, here and here. But now I feel like these newest works are being put up to attract my notice. Or maybe I'm just a paranoid narcissist. But it's like he's playing low-rent Dr. Moriarty to my bargain-basement Sherlock Holmes. But why? Who knows? I expect more clues to follow. Anyhow, here is the latest bit of scariness:

This is on the side of the traffic signal box at 1st & Wall. What's the significance of that location? Unknown, but I'm determined to make sense of it until I can plot his next move, corner him in an alley and scream "Checkmate, scary skull guy! Game over!" Go ahead, drop more clues in my path. The showdown will be dramatic. I promise.

Or maybe he's just some guy who likes to draw on stuff when the opportunity presents itself. That's also possible.