A canine combat vet who used to sniff out roadside bombs in afghanistan is now helping protect the pentagon. cnn's pentagon correspondent barbara starr has that story. >> reporter: when emmy comes to work at the department of defense alongside pentagon police officer eric harris, her nose is already on alert checking, pausing, sniffing. emmy is trained to detect explosives, but this 6-year-old lab is also a combat veteran, the first on the pentagon's canine force. what did you know about emmy before she came to you? >> she came to work for us, did two hours in afghanistan with a marine corps u...