On December 15, 2009, at 1616 eastern standard time, radar contact was lost with a Cirrus Design Corp SR22, N723LJ, while in cruise flight over the Gulf of Mexico. As of November 22, 2010, the airplane had not been located. The airplane was presumed destroyed and the certificated private pilot was presumed killed; however, as of the date of this report, the location of the airplane, and the condition of the certificated private pilot were not known. Visual meteorological conditions prevailed and no flight plan had been filed for the personal flight that departed Albert Whitted Airport (SPG), St. Petersburg, Florida, about 1520. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. According to the pilot's wife, the pilot, who was a retired doctor, had lunch at home about 1130. He had a meeting scheduled with a business partner in the local area. She was not aware of him having any plans to go flying. The pilot's wife did not have any further contact with the pilot. She subsequently learned that the pilot did not attend the meeting, and when he did not return home, contacted local police. The airplane was based at SPG. A witness at a fixed-based-operator, who spoke with the pilot, stated that he asked to have the airplane taken out of its hangar, and the pilot sounded the same as he normally did. Witnesses at SPG observed the pilot at the airport and reported observing the airplane taxiing for takeoff. According to the Federal Aviation Administration (FAA), review of air traffic control communications revealed that the airplane was cleared for takeoff from runway 7, with a left turn to the west, by the SPG air traffic control tower at 1517. At 1520, the airplane was approved for a frequency change. There were no further known communications with the airplane. Radar data revealed a radar target consistent with the airplane's departure. The target subsequently proceeded westbound over the Gulf of Mexico and climbed to an altitude of 9,900 feet, where it remained until radar contact was lost. The last radar target was observed at 1616:35, about 150 miles west-southwest of SPG at an altitude of 9,900 feet, and traveling at a ground speed of 167 knots. The pilot's wife was not aware that the pilot's airplane was missing until December 17, 2009, and the airplane was subsequently reported as overdue to the United States Coast Guard at 1711. Search and Rescue personnel conducted three sorties which covered 1,890 square miles over 13 hours with negative results. According to FAA records, the four-seat, low-wing, fixed-gear airplane, serial number 2402, was manufactured in 2007, and issued a standard airworthiness certificate on March 13, 2007. It was constructed primarily of composite materials, and equipped with a Teledyne Continental Motors IO-550-N, 310-horsepower engine. The airplane was purchased new by the pilot through a limited liability company on March 15, 2007. Review of maintenance records revealed that the airplane's most recent annual inspection was completed on March 25, 2009. At that time, the airplane had been operated for about 400 hours. In addition, an oil change was performed on August 8, 2009, at a total time of 470.4 hours. The pilot had flown the airplane for about 100 hours since the annual inspection. The airplane's last known refueling was performed on November 20, 2009, when 19.4 gallons of 100-low-lead aviation gasoline was added to the airplane at SPG. The pilot's family did not believe the airplane had been flown in-between November 20, and December 15, 2009. The pilot, age 50, held a private pilot certificate, with ratings for airplane single-engine land and instrument airplane. He reported 410 hours of total flight experience on his most recent application for an FAA third-class medical certificate, which was issued on June 23, 2008. Review of the pilot's logbook revealed that the most recent entry was dated November 20, 2009. At that time, the pilot had accumulated about 700 hours of total flight experience, which included about 520 hours in the accident airplane. The pilot had logged approximately 1.4 and 14.7 hours during the 30 and 90 days, which preceded the flight; respectfully.