Green’s Dictionary of Slang

crazy, insane.

1991		M.B. ‘Chopper’ Read Chopper From The Inside 25: A nut case crew of boys from the western suburbs.
2000		J.J. Connolly Layer Cake 273: It’s one thing shooting a nut-case Nazi who’s probably known to Interpol.
2013		T. Robinson Hard Bounce [ebook] [H]omeless addicts, nutcase bums, and runaway teens.