CLACKAMAS COUNTY, Ore. (KOIN) — A citizen discovered a human skull in a remote part of the Warm Springs Indian Reservation, according to police.

The citizen was salvaging some wood from an old dock Monday along Tenino Road when they noticed a round item on the ground, rolled it with their foot, and realized it appeared to be a human skull, Warm Springs Tribal Police Chief Bill Elliott wrote in a press release.

The citizen called police and detectives searched the area, finding “several other bones that were of interest,” police said. The FBI was notified and agents went to the reservation to process the site.

A preliminary examination by the medical examiner’s office revealed the remains could have been in the area for anywhere from one to ten years. Warm Springs Tribal Police said they would check their database for missing people or runaways from the last 10 years as an initial step in the investigation.