Gary is a former Baltimore Homicide Lieutenant. The non-fiction book Homicide: A Year on the Killing Streets was based on a year that author David Simon spent with Gary's unit. When the series came out (based loosely on the book) Gary was eventually given a role as the SWAT team commander. The character of Gee is based on him. If you read the book, you will notice nearly all of season one is based on it. There was a real Adena Watson, her real name was Latonya Wallace and to my knowledge the case remains open to this day.