Sacramento police arrested two suspects in the dismemberment-slaying of a 33-year-old man whose severed body parts were found stuffed into tool boxes kept in the trunk of a parked car. Timothy Sugars, 27, an unemployed construction worker, was taken into custody after officers investigating an apparently unrelated complaint found him in possession of the head and other body parts of a man later identified as Stephen Rogers. Robert Penny, 29, was arrested after further questioning of Sugars, but police Sgt. Bob Burns said there was a "lot of ground to cover" before the investigation is completed. "At this point," Burns said, "we have not figured out the motive . . . or located the rest of the body."