"He is wearing a denim jacket and flanel shirt."
What color is the shirt? In the dark, are you sure it's not body armor? If you can tell it's flannel, it's not a dark alley.
I've lived in and around cities for more than 50 years - D.C., Baltimore, Richmond. I don't go into alleys after dark.
Having said all of that, at real close range I'd shoot 'em in the face and then worry about follow-ups.
Anybody remember when the guys in Baltimore started a contest in the alley behind a bar? They used fishing rods to cast hot dog chunks down the alley in order to hook a rat. Really.
You can't make this stuff up.
Baltimore Bar Sponsors Fishing Contest - For Rats. June 27, 1994 ... alleys for the Yellow Rose Saloon's second annual rat fishing contest Sunday. ...
articles.orlandosentinel.com/keyword/second-rat - Cached