A forensic expert has said screams heard on a 911 call moments before Trayvon Martin was killed were not those of George Zimmerman.
Zimmerman, 28, claims he shot the teenager in self defence after he was attacked and and told police he was the one who could be heard crying out in the recording.
However, leading voice identification expert Tom Owen has said he is certain the screams do not belong to Zimmerman after using specialised biometric software to compare the voices.