On May 9, 2001, about 0805 hours Pacific daylight time, a Cessna 421C, N26560, veered off the runway and collided with a fence during landing rollout at the Angwin-Parrett Field, Angwin, California. The airplane was owned and operated by the pilot, and it was substantially damaged during the mishap. The private pilot and two passengers were not injured. The third passenger received minor injuries. Visual meteorological conditions prevailed at the time, and no flight plan was filed. The business flight was performed under 14 CFR Part 91, and it originated from Stockton, California, about 0735. The pilot and a passenger indicated to the National Transportation Safety Board investigator that the touchdown felt normal. The pilot also reported that he believed the right brake locked up during rollout. Thereafter, he was not able to maintain directional control of his airplane. The pilot subsequently reported that his total experience flying airplanes was 1,117.8 hours. His experience flying the Cessna 421C was 312.5 hours. According to the Federal Aviation Administration coordinator, an examination of the runway revealed evidence of approximately 600-foot-long right main landing gear tire skid marks starting an estimated 500 feet beyond the landing threshold of runway 16. The skid marks terminated near where the airplane veered off the west side of the runway, about midfield. The airplane stopped upon traversing a field and colliding with a fence pole. At the time of the mishap, the wind was calm. The reason for the brake lockup was not determined.