Tracy Martin, Trayvon Martin's father, was one of the defense's last witnesses on Monday.
Defense attorneys wanted Martin to talk about what happened at the police station when officers played the 911 tape that had caught screams from the confrontation between Trayvon Martin and George Zimmerman.
Martin testified that when the tape ended, the officers asked him if he could identify the voice yelling for help. On the stand, he told them he could not. Several officers had testified earlier that they took that conversation to mean Trayvon Martin was not the voice yelling for help.
Sybrina Fulton, Trayvon's mother, testified earlier in the trial that the yells were from her son. Trayvon's brother also testified for the prosecution that the voice on the tape was Martin.