SANFORD, Fla. (AP) — The mothers of Trayvon Martin and George Zimmerman listened Friday to the same 911 recording of someone screaming for help, and each said she was convinced the voice was that of her own son. The starkly conflicting testimony over the potentially crucial piece of evidence came midway through Zimmerman's murder trial in the 2012 shooting of the unarmed 17-year-old. "I heard my son screaming," Sybrina Fulton, the teenager's mother, said firmly after she was played a recording in which distant, high-pitched wails could be heard in the background as a Zimmerman neighbor asked a dispatcher to send police.