Federal authorities say they're making progress in their investigation of recent vandalism at the Grand Canyon.
The National Park Service says investigators have located people considered "persons of interest" in the defacing of a rock near an overlook on the South Rim.
The Park Service says the case remains open and under investigation so it won't be releasing any additional information at this time.
A visitor had photographed the rock with "Evans 16" spray-painted in black, and a man and woman walking away from it on May 22.
Defacing a natural feature is a federal offense that carries jail time and fines.
The Park Service didn't say how the people were located but it thanks members of the public "for their interest in and assistance with the investigation."