The skull was found on May 18, about two miles east of Lake Fulmor on Highway 243 when a driver on his way home stopped along the road to go to the bathroom.
"While he was doing this he saw something that appeared to be a skull. He notified the sheriff's department and we immediately responded to the location," said Sgt. Joe Borja, Riverside County Sheriff's Dept.
Detectives have put together a rough sketch of the victim based on the shape of the skull. They said it was likely a white or Hispanic male, somewhere between 20 and 40 years old. But hair and eye color remain unknown and they probably won't be able to get a DNA sample. They do have some dental record which could assist in identification.
Because only the skull was found, it is difficult for detectives to determine when exactly a crime occurred.
"When you just find the skull, it's hard to determine when that skull made its demise," said Borja. "But we do have other techniques - we go through missing person's reports, any other incidents that may have occurred that we're missing people for whatever reason and we try to work our way backward."