This is a story from Chicken A Soup for the Cat and Dog Lover's Soul - the story itself is online here and the author's site is available there as well. I hope this story touches anyone who reads it as much as it did me.
IOt can read it on the site Sherlock Bones - yet another pet detective (sounds like an intereesting job!)
http://www.sherlockbones.com/chickensoup.php