This singer played a detective in 3 straight 60's films: "Tony Rome", "The Detective" & "Lady in Cement"
The film begins on his last day inside, and shows him to be .... rather chillingly 
plays out against the collective cell block singing of the ... Tajima (Jo Shishido), is 
a cocky, resourceful private eye who owns the Detective Bureau 2-3 of the title.