The parents of Trayvon Martin, Tracy Martin and Sybrina Fulton, arrive for the 20th day of the George Zimmerman trial in Seminole circuit court July 8, 2013 in Sanford, Florida. Zimmerman has been charged with second-degree murder for the 2012 shooting death of Trayvon Martin. (Photo by Joe Burbank-Pool/Getty Images)
SANFORD, Fla. (AP) -- The lead detective in George Zimmerman's second-degree murder case says
Trayvon Martin's father told him that screams for help on a 911 call
weren't his son's.
Officer Chris Serino was called by the defense Monday to testify about a meeting with Martin's father in the days after the Miami teen was fatally shot by Zimmerman.
Serino says at the meeting, when Tracy Martin listened to the 911 recording and was asked if it was his son, Tracy Martin said "no."
RELATED: Martin's dad says he never denied it was son on 911 call
Tracy Martin was in the courtroom Monday as Serino recounted the meeting.
Convincing the jury of whose voice is on the tapes is important because it would help them decide who was the aggressor in the confrontation. Relatives of Martin's and Zimmerman's have offered conflicting opinions about who is heard screaming.
Zimmerman is pleading not guilty to second degree murder, claiming self-defense.
KYLE HIGHTOWER, Associated Press