By FELICIA FONSECA A 9-year-old Arizona boy pleaded guilty Thursday to negligent homicide in the shooting death of his father's roommate. Under a plea agreement, two charges of premeditated murder for the deaths of the father and the roommate were dropped. Police said the boy used a .22-caliber rifle to shoot the men as they returned home from work.The boy's plea spares the rural community of about 4,000 from what would have been an emotional trial and prevents the boy from serving time in the state juvenile corrections system or being tried as an adult.The boy has not yet been sentenced.