's a dangerous , secretly unhinged guy who could easily have killed a president because it made him feel powerful . 
(ROOT (S (VP (VBZ 's) (NP (NP (DT a) (JJ dangerous) (, ,) (ADJP (RB secretly) (JJ unhinged)) (NN guy)) (SBAR (WHNP (WP who)) (S (VP (MD could) (ADVP (RB easily)) (VP (VB have) (VP (VBN killed) (NP (DT a) (NN president)) (SBAR (IN because) (S (NP (PRP it)) (VP (VBD made) (S (NP (PRP him)) (VP (VB feel) (ADJP (JJ powerful)))))))))))))) (. .)))
(ROOT (S (VP (VBZ ) (NP (NP (DT ) (JJ ) (, ) (ADJP (RB ) (JJ )) (NN )) (SBAR (WHNP (WP )) (S (VP (MD ) (ADVP (RB )) (VP (VB ) (VP (VBN ) (NP (DT ) (NN )) (SBAR (IN ) (S (NP (PRP )) (VP (VBD ) (S (NP (PRP )) (VP (VB ) (ADJP (JJ )))))))))))))) (. )))