sybrina_fulton_3.jpegSANFORD, Florida (AP) – The mother of black teenager shot and killed by a neighborhood watch volunteer has testified that screams for help captured on audio of a police call came from her 17-year-old son.

Sybrina Fulton took the witness stand Friday morning during the trial of George Zimmerman, the former neighborhood watch volunteer charged with murder in Trayvon Martin's shooting death. Zimmerman has pleaded not guilty and says he shot the teen in self-defense during a fight.

After the audio was played, prosecutor Bernie de la Rionda asked Fulton, "Who do you recognize that to be?'' She replied, "Trayvon Benjamin Martin.''

Identifying the screams on the police call could be critical to the case because it may help determine who was the aggressor during the scuffle between Zimmerman and Martin.