On March 11, 2015, at 1243 central daylight time, the pilot of a Beech B19, N774TA, ditched in Lake Ozark, Osage Beach, Missouri, after oil pressure was lost and the engine seized. One passenger was seriously injured, but the pilot and another passenger escaped injury. The airplane was substantially damaged. The airplane was registered to GDS Properties and operated by the pilot, both of St. Charles, Missouri, under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan had been filed. The cross-country flight originated from Grand Glaize-Osage Beach Airport (K15), Osage Beach, Missouri, about 1225, and was en route to Creve Coeur Airport (1H0), St. Louis, Missouri.The pilot told a Federal Aviation Administration (FAA) inspector that everything appeared to be normal when he conducted his preflight inspection, although the oil did appear darker than usual. There was 6 quarts of oil on the dipstick and the oil had just been changed two days before. During the engine run-up, all engine instruments were "in the green." Shortly after takeoff, when the airplane had attained an altitude of about 2,800 feet, he noticed the oil pressure was dropping and he turned back towards K15. Shortly thereafter, the propeller stopped and the engine seized. He ditch in Lake Ozark. The occupants exited the airplane and climbed out on the wing. The pilot said that as they awaited rescue, he thought he smelled a twinge of burnt oil. The FAA inspector examined the airplane and verified there was ample fuel on board, and that it was blue in color. He found the throttle linkage connected. The engine could not be turned by hand. The inspector said he could not find the oil dipstick when the airplane was recovered from the lake. The pilot, however, was adamant that he had replaced the dipstick after checking the oil. On April 15 and 16, 2015, the engine was disassembled and examined at Dawson Aircraft in Clinton, Arkansas. The oil dipstick was missing, but more than 4 quarts of oil and only 1 to 2 cups of water were drained from the engine. There were no signs of oil in the engine cowling, and there were no oil streaks underneath the fuselage. The no. 2 middle bearing on the crankshaft had seized. The third bearing aft between the two banks of cylinders had rotated, and the bearing for the no. 3 connecting rod had rotated. There was evidence of severe heat distress and mechanical damage to the no. 3 rod bearing. The latter had started squeezing out the sides of the connecting rod end. The no. 4 piston wrist pin plug was deformed and had damaged the side of the piston. Aluminum pieces and shavings were noted throughout the engine. The engine parts appeared to have been manufactured by Superior Air Parts, Inc., and not by Textron Lycoming.