A turtle with GPS finds a pot patch in Rock Creek Park.

WASHINGTON, DC (WUSA) -- You might call him a pint-sized crime fighter. A box turtle equipped with GPS helps police nab a suspect growing marijuana in Rock Creek Park.

Just south of the DC/Maryland line, a turtle wearing a GPS device for research purposes makes an amazing discovery.

"The ranger in charge of the program discovered the turtle in the middle of a marijuana field," Sgt. Robert Lachance of the U.S. Park Police says.

Cindy Gossage who's been walking the trails for years isn't surprised.

"I come back here to walk my dogs, and I've found several different marijuana fields back here."

Growing marijuana on U.S. park land is never a good idea, and it's illegal. So U.S. Park Police set up surveillance.

Sgt. Lachance says, "We soon discovered we had a culprit who was actively working the field."

Police say that culprit is 19 year old Isiah Johnson of Chevy Chase. He's now in custody and will be extradited back DC to face drug charges.

"He felt like he had a layer of security, but he probably never counted on a turtle with a tracking device leading us to that location and finding the field."

And this may not be the end of the turtle tracking tale. The little fella and his GPS device are back out in the woods somewhere.