At approximately 0846 central time, a Cessna T210N crashed following a loss of control during cruise flight near Mission. The pilot and two passengers were killed. A Mexican IFR flight plan was filed by the pilot for a business flight from Matamoros, Mexico, to Torreon, Mexico. The pilot was in cruise flight when he contacted Reynosa Approach and requested a climb from 6,000 feet to 8,000 feet, which was approved. Controllers noted the flight was five to seven miles north of course when the pilot was asked by Reynosa Approach to verify his position. The pilot replied we have a problem here with my (not intelligible). I will try another radio. The flight crossed the US-Mexican Border as the radar controller tracked the aircrafts erratic path. The airplane was observed in rapid descent passing 5,500 feet, and again at 4,000 feet until it disappeared from radar. The pilot was reported to have accumulated over 21,000 flight hours.