Carrie Templin, a spokeswoman for the agency, said the petroglyph panel, which depicts a human figure with two arms and one leg, was chiseled out of the cliff face at Cottonwood Point Wilderness Area at some point between April and Sept. 7 of this year, KPHO-TV, Phoenix, reported Thursday.

"Where there once was a petroglyph of a human figure, now only a large cavity in the sandstone cliff face remains," Templin said. "These cultural sites are fragile and irreplaceable traces of an ancient history. They are a legacy we should all help preserve."

Templin said a $5,000 reward is being offered for information leading to the arrest and conviction of a suspect in the case.