Officials are investigating paintings and drawings of eerie faces found on rocks across the West in some of the country's most recognizable national parks.
National Park Service spokesman Jeffrey Olson says the probe stemmed from a post on a California-based hiking blog about a woman who traveled across the West, apparently using acrylic paint to leave images on the rocks.
The blogger, Casey Schreiner of modernhiker.com, says the New York state woman documented her work on Instagram and Tumblr.
The woman's photographs have sparked a furor online, with people blasting the paintings on websites such as Reddit.
National parks agents have confirmed the vandalism in Yosemite and Death Valley National Parks in California, Canyonlands and Zion in Utah, and Crater Lake in Oregon.
Investigators also are looking for vandalism in other states the woman visited.