At about 0950 Eastern time, the airplane was substantially damaged while landing; the Commercial pilot and three passengers were not injured. Visual conditions prevailed. About five minutes after takeoff, the pilot noticed a high oil temperature indication for one of the engines. The pilot elected to return to the departure airport. During touchdown, the left main landing gear collapsed, and the airplane veered right. The airplane traveled off the right side of the runway, struck a ditch and came to rest upright.