If you haven't seen this story yet, a New York woman traveled through a bunch of national parks (Death Valley, Zion, Arches, RMNP, and others) this summer and painted "artwork" all over with her Instagram tag "creepytings." She thankfully documented most of it on her Instagram and Tumblr pages and was identified as Casey Nocket of NY.
Here is the petition on whitehouse.gov to prosecute her to the fullest extent:
https://petitions.whitehouse.gov/petition/press-charges-casey-nocket-finesmax-community-servicejail-timeetc-httpgooglhy4yqj-defacing-np-nm/1y8xJBGm
And here are some articles about it:
http://calipidder.com/wp/2014/10/tracking-serial-vandal-national-parks/
http://www.modernhiker.com/2014/10/21/instagram-artist-defaces-national-parks/