He says he saw kids yelling and saw Nana, the 4-year-old pit bull, approach a young girl.
Devine says he got the dogs attention and she came within 5 feet of him. But he claims he couldn't make it inside of his home on Quail Lane, so he shot Nana once.
Police say he does have a valid pistol permit and it is a properly registered gun.
Nana wandered back to her home on Partridge Lane and died on the front steps.
So far, no charges have been filed.
Police say there was one prior documented account of a vicious pit bull in the area last year.