Source: Authorities are continuing to investigate a collision last week that led to the death of a Richmond bicyclist.Luther M. Jefferson, 62, of the 1800 block of Maddox Street, was riding a bicycle southbound on Mechanicsville Turnpike at 3:34 p.m. Thursday when he and a box truck collided near an Interstate 64 exit ramp. Jefferson died several hours later at VCU Medical Center. The medical examiner has yet to determine the exact cause of death. Police said the results of an investigation conducted by the department's crash team will be forwarded to the office of Commonwealth's Attorney Michael N. Herring for possible charges. The driver of the box truck, whose identity has not been released, was uninjured.