Ocala police have yet to charge three out of four men allegedly involved in a cold blooded murder.  Kenard Singh, 20,  was arrested last week in connection with the murder of 55-year-old Doug Tripp during a home invasion robbery. But the man suspected of firing the shots, 18-year-old Brenton James Crabtree has not yet been charged. He is already in police custody for robbing Tripp's home before the night of the murder. Two other men  police think are involved in the shooting,  have not yet been arrested.