Raffael Medlin says he saw accused murderer Gregorio Arenas shoot his friend in cold blood after pistol whipping him in front of their apartment. He says he then walked into their apartment and pointed a gun at him and his friends, warning if they talked to police he would come back and kill them.The Arenas defense maintains Medlin is lying, his story changing several times and that his drinking issues may have clouded his memory. They say another man, known only as “El Pollo,” the Chicken, is the man who killed Albertano Guerro Trejo, 29, in July 2012.The opposing views clashed Tuesday as the Arenas murder trial got under way at Warren County Courthouse.