Thurston County deputies said they found two cats dead Wednesday, adding to the total of nine found Monday and Tuesday.
Tuesday, a veterinarian examined a cat killed and determined the injuries were consistent with the other cats recently killed in the area.
Investigators said there is no question these animals are being killed by a human.
"These animals are all being displayed. It's almost like a trophy, I've said it's almost like a arsonist. Where they light the fire and come back to the scene to watch the reactions. These animals are always being left in busy, public areas for people to find it,” said Erika Johnson, Thurston County cruelty investigator.
The reward for information has increased to $30,000.