Police are hoping that a baseball cap found inside Zoo Boise will help them track down the suspects in the beating death of a monkey.
A break-in at the zoo early Saturday left a Patas monkey dead from blunt force trauma to the head and neck.
Police are analyzing blood found at the scene to determine if it came from the monkey or one of two human intruders.
Police say two males wearing dark clothing were spotted by a security guard at 4:30 a.m. outside the fence near the primate exhibit.
Both fled and police have been unable to find them.
But they said late Saturday night that a grey baseball cap with a skull design was probably left behind by one of them.