But the executive director of the Detroit Dog Rescue, Kristina Rinaldi, says it's a case of mistaken identity and that Diggy isn't a pit bull at all.
"Diggy is an American Bulldog and all of his paperwork says so," Ms Rinaldi told Detroit Free Press.
However, according to The Detroit News, the rescue group described the pup as a "pit bull mix" in a Facebook post on May 31 advertising his adoption. The post has since been removed.
Police have said that if Mr Tillery can obtain veterinary proof that the dog is not a pit ball, the matter will be resolved and Diggy can stay where he is.
"If he can show that it's not [a pit bull], then it'll be fine," Police Lt. Todd Hasselbach, told The Detroit News.
"He just has to keep those papers on him because his neighbours are gonna keep calling."