A group of police dogs in Washington state are being trained in the fight against illegal marijuana use.

The dogs are useful because the undercover marijuana plants are usually booby-trapped and heavily guarded. Dogs can sniff out where suspects are hiding and flush them out.

"These organizations are in many cases armed. So, it's almost without exception that we find firearms in these groves," Washington State Patrol's Lt. Rich Wiley said.

Some of the K-9s are being trained to be lowered from a police helicopter into an area thought to be the location of an illegal marijuana growing operation.

"I'm reading the dog constantly, looking for any changed behavior," Spokane Police Officer Craig Hamilton said. "We are able to send him out ahead of us, clear the camp sites, as well as the actual crops."
    
Washington state is the second largest producer of marijuana in the United States.