The nr2 engine began backfiring while climbing through 1000 feet following a runway 09 takeoff. An unsuccessful attempt was made to feather the right propeller, while attempting to position the airplane for a landing at the origin airport. The copilot reported that the airplane arrived at a position that was abeam the approach threshold for runway 09, at 500 feet above the ground, with an airspeed of about 95-100 knots. The airplane was turned south toward the departure runway. A decision was then made to divert to the international airport. According to the copilot, the throttle was placed in the maximum power position without increasing the propeller control. The airplane then turned right, back to a westerly heading, and subsequently crashed beside a canal about three miles west of the departure runway. PROBABLE CAUSE: “Failure of the #11 cylinder on the right (#2) engine, which resulted in an in-flight fire and loss of power in that engine; and a malfunction/failure of the #2 feathering system, which led to a subsequent forced landing before the flight crew could return to the airport. A factor related to the accident was failure of the flight crew to increase the left (#1) engine rpm (in accordance with emergency procedures) after loss of power in the #2 engine. Full narrative available.”