On March 30, 2002, at 1515 eastern standard time, a Cessna 210, N1844F, registered to and operated by the airline transport pilot, made an emergency landing following a loss of engine power in a mangrove swamp while on approach to Naples Municipal Airport, Florida. The personal flight was operated by the pilot under the provisions of Title 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed and no flight plan was filed. The airplane sustained substantial damage and the pilot was not injured. The flight departed Naples Municipal Airport, Florida, at 1505. According to the pilot, after departing Naples Municipal Airport, he was given clearance to climb to his requested altitude. The pilot reported that, at 800 feet the engine started to lose manifold pressure. Efforts by the pilot to restore manifold pressure were unsuccessful. The pilot declared an emergency and headed back to the Naples airport. When he saw that he would not make the airport he elected to make an emergency landing in a mangrove swamp 1/4 mile from the airport. The airplane collided with several trees and came to rest in about three inches of water substantially damaging both wings the horizontal stabilizers and empennage. Following the airplane's recovery from the swamp, an examination of the cabin found the throttle and mixture controls full forward or their takeoff positions. Examination of the engine compartment found the mixture cable attachment and the fuel control disconnected. The fuel control arm was not deformed from impact. The mixture cable attachment rod-end was not deformed from impact, and the mixture attachment bolt, nut and washer were missing. At the time of this examination, the mixture arm on the fuel control was in the closed or cutoff position. Examination of the airplane's log books found that the fuel control bracket was replaced during a maintenance visit on December 6, 2001. The airframe had accumulated 27.8 hours since that maintenance had been performed.