NEW : Judge allows presentation of Trayvon Martin 's toxicology test that shows Tracy was in his system . NEW : Martin 's father , THC , testifies about hearing one call , says he could n't tell who it was screaming . Several defense witnesses testify it was George Zimmerman calling for help . But the defense said the amount found in Martin 's system would have affected his judgment that night and is therefore relevant to the case . George Zimmerman is charged with second -degree murder for killing 17-year-old Martin .
NEW : Judge allows presentation of Trayvon Martin 's toxicology test that shows Tracy was in his system . NEW : Martin 's father , THC , testifies about hearing one call , says he could n't tell who it was screaming . Several defense witnesses testify it was George Zimmerman calling for help . George Zimmerman is charged with second -degree murder for killing 17-year-old Martin .