Zoo Boise was closed Saturday morning while police investigated a break-in that left a male Patas monkey dead. Detectives recovered blood evidence and are testing it to see if it belongs to the monkey or to one of the break-in suspects. They also found a ball cap they believe one of the suspects dropped. The grey cap has a white skull and wings design with a red logo.

A zoo security guard called the police at 4:30 a.m. after seeing two men in dark clothes — one inside the zoo grounds, the other outside the fence near the primate exhibit.

The men ran when they saw the guard. The man inside the fence ran into the interior of the zoo. Police arrived, along with Zoo Director Steve Burns. Police searched the zoo twice, once with a thermal imager, but found no one.

Burns said they were searching when they heard a groaning sound. “We didn’t know what it was, whether it was an animal or a human,” said Burns.

It was the severly injured monkey lying next to the fence near where the guard had seen the suspects. The monkey appeared to have a head injury.

The zoo veterinarian Holly Peters arrived within 15 minutes, Burns said, but the monkey died a short time later. Peters performed a necropsy Saturday afternoon that revealed the animal died of blunt force trauma to its head and neck.

The monkey shared a cage with another Patas monkey that was not harmed. Police have not said how the men got into the zoo, nor how they were able to open the monkeys’ cage. None of the other animals at the zoo was harmed.

The zoo is never left unattended, said Burns. A guard is on duty at the zoo from 5 p.m. to 7 a.m., when staffers are not there, every day of the year. A guard was on duty Saturday at the time of the break-in.

Burns said there have not been other break-ins during the 15 years he’s been at Zoo Boise. Safety of visitors, staffers and animals is paramount at the zoo, he said. The staff hasn’t yet had time to review what happened Saturday to decide what security changes might be made in the future, Burns said.

Staffers greeted news of the monkey’s death with “a lot of shock, a lot of tears, a lot of devastation,” said Burns. “One of the staffers said it feels like someone broke into their house and harmed one of their children,” said Burns.

The zoo’s residents are not pets, he said, but staffers who care for animals for many years build attachments to them.

“Visitors also get attached to favorite animals. And the monkeys are always among the favorites,” said Burns. “It’s going to be hard to explain to kids that there are people in the world who would do something like this.”

Patas monkeys are ground dwellers from the African plains. Adults like the monkey that was killed stand about two-and-a-half feet tall and weigh 35 pounds. They are not endangered in the wild, but are rare in zoos, Burns said. Only 52 Patas monkeys live in U.S. zoos.

Both of Zoo Boise's Patas monkeys came from the Lowry Park Zoo in Tampa Bay, Florida three years ago.

"Because monkeys are social animals we are concerned about the welfare of the remaining animal," saidBurns. The zoo will explore opportunities to find a replacement or move the remaining animal to another zoo.

Police are asking anyone with any information on this case is urged to contact Crime Stoppers at 343-COPS, or log onto www.343cops.com, or text CRIMES or 274637, subject: Tip236. A citizen can remain anonymous. A reward of up to $1,000 is offered by Crime Stoppers for information leading to the arrest of criminal suspects.

Anna Webb: 377-6431