A BL list of Police x civilian/gangster/any

http://www.mangago.me/read-manga/haga_kun_wa_kamaretai/
http://www.mangago.me/read-manga/under_grand_hotel/

http://www.mangago.me/read-manga/ibitsu_na_koi_no_seesaw_game/

honto yajuu is THE BEST

Also these
http://www.mangago.me/read-manga/see_you_at_the_crosswalk/?av=1 - uke is cop
http://www.mangago.me/read-manga/on_doorstep/ - ex cop and thief
http://www.mangago.me/read-manga/sugar_dog_life/ - this is new and ongoing but fits your description