What kind of snake is this? (pic)?

My 7 year old recently found a snake I originally thought it was a garter but I'm not so sure anymore. My husband said it could be a northern brown snake but again we are not sure. My son found it a slug yesterday and the snake ate it. Here is the pic a href="http://www.flickr.com/photos/36511155@N06/5811464481/" rel="nofollow"http://www.flickr.com/photos/36511155@N0…/a