Determining screams on 911 tape dominate Zimmerman trial ← Related Article Visit The Boston Globe Share on Twitter Share on Facebook Comment on this Scroll to top of page Joe Burbank / Pool The parents of Trayvon Martin, Sybrina Fulton (left) and Tracy Martin, listened to testimony in Seminole Circuit Court on Monday. Joe Burbank / Pool George Zimmerman winked at his defense counsel, Don West, in the court room. Joe Burbank / Pool John Donnelly, a friend of Zimmerman, cried on the witness stand after listening to screams on a 911 tape entered into evidence. Joe Burbank / Pool Mark Osterman, a friend of Zimmerman, testified about the type of gun Zimmerman owned. Joe Burbank / Pool Zimmerman and his attorney conferred during a recess in the courtroom. Joe Burbank / POOL Sanford police Officer Chris Serino testified for the defense on Monday. Joe Burbank / Pool Sondra Osterman, a friend of Zimmerman, listened to the 911 tape while testifying.