someone who obviously knows nothing about crime 
(ROOT (NP (NP (NN someone)) (SBAR (WHNP (WP who)) (S (ADVP (RB obviously)) (VP (VBZ knows) (NP (NP (NN nothing)) (PP (IN about) (NP (NN crime)))))))))
(ROOT (NP (NP (NN )) (SBAR (WHNP (WP )) (S (ADVP (RB )) (VP (VBZ ) (NP (NP (NN )) (PP (IN ) (NP (NN )))))))))