I was on that trail a few days ago and saw two instances of blue graffiti (had to turn around early, unfortunately.) I figured they had to be some of the ones in the news story, though the story describes them as "blue and white" and blurs the pictures. Two things about that, though:
1. I also noticed that someone had left a modest-sized blue-and-white graffito at a lodging outside the Park where graffiti have otherwise been pretty scarce. I took a picture, but I'm not a connoisseur of graffiti and can't tell if it has anything in common with the ones along the trail.
2. Tonight, back in the Bay Area, I noticed a rock on the edge of a parking lot with blue graffiti that looked very similar (in color and style) to the ones I'd seen along the trail. I have no way of telling if that color and style are in vogue among graffitists all over California or if, possibly, I keep crossing paths with whoever tagged the rocks in the Park. Is there any point in seeking out whoever is investigating the tagging, or would I just be bothering them with useless information?
I did get pictures of the four pieces that I saw, in the Park and out. One of the four is on a surface that gets driven over so it'll eventually disappear. The ones on rocks all look like they'll be there till someone removes them.