Testimony began Tuesday morning in the murder trial of Brandon Trevino. The 19-year-old is charged in the shooting death of his girlfriend, 17 year old Katrina Carrasco in January 2006. Samantha Rodriguez, a friend of Katrina Carrasco, said today in court that she was on the phone with Katrina when the shooting occurred. She said Brandon and Katrina were arguing, that she heard Brandon threatening to shoot Katrina, then heard a pop. She acknowledged that the testimony she gave Tuesday was different than what she told a detective the night of the shooting...When she said she thought Brandon and Katrina were "just playing," and not seriously arguing. Jury members also saw graphic photos of Katrinas bullet wound, listened to the 9-1-1 call from Brandon Trevino, and heard from detectives who investigated the shooting. Prosecutors will resume presenting their case Wednesday morning at nine a.m.