Published: Jul 11, 2012 10:55 AM EDT

FORT LAUDERDALE, Fla. (AP) - The defense is set to begin its case in the attempted murder trial of a Florida teenager in a savage kicking and stomping attack on a 15-year-old girl.
    
Attorneys for 17-year-old Wayne Treacy were expected Wednesday to begin presenting their insanity defense after the prosecution rests.
    
The defense claims Treacy suffered from post-traumatic stress disorder when he assaulted Josie Lou Ratley outside a middle school in 2010. The disorder supposedly started after Treacy's brother committed suicide by hanging himself a few months earlier.
    
Now 17, Ratley almost died and suffered permanent brain injuries. The attack happened after the two exchanged taunting and insulting text messages, culminating with one from Ratley referring to Treacy's dead brother.
    
Treacy faces a possible 50-year prison sentence if convicted of attempted first-degree murder.

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