A Difficult Question of Copyright

I, like many photographers, routinely use Google's Image Search in order to find people that have stolen my photos in order to issue DMCA takedown notices.  Recently, I came across a weird situation. Several years ago, I took this photo depicting some "found" artwork at the site of the then-soon-to-be-demolished Good-Latimer tunnel in Dallas' Deep Ellum neighborhood:

Demon Face

I photoblogged it in October of 2007 (and note that I don't sell prints of it) and kind of forgot about it (that was almost six years and ~2,000 photos ago!).

So, imagine my surprise when Google Image Search returned a hit that showed some charlatan had taken my image, cleaned it up and made a (admittedly cool-looking) t-shirt from it:

ripoff

And here's an imperfect overlay of both.  The oblique angle that I took the photo at is apparent in the t-shirt...the other variations are obviously from cleaning up the photo a bit and vectorizing it.

overlay

Normally, I would've fired off a DMCA notice to Redbubble and had the t-shirt removed, but in this case, my photo is of another's artwork, so it's a grey-area.  The original work doesn't exist anymore, having been demolished in late 2007 along with the rest of the graffiti-covered Good-Latimer Tunnel and determining the original artist would be nigh-impossible. And, since I don't own the copyright to the original work, going after this image thief would be a pointless endeavour.  So, instead it looks like I get to sit back and watch someone else make money off a derivative of my work that was originally a derivative work to begin with.

And it makes me damn angry.

And if I make my own t-shirt of this design, what're my rights?