Complex sentence: His family was contacted by the U.S. Securities and Exchange Commission, the Internal Revenue Service and the Federal Bureau of Investigation, but no one knew his whereabouts until his death of throat cancer on February 16,1999, in Apopka, Florida.
Split into simpler sentences: His family was contacted by the U.S. Securities and Exchange Commission, the Internal Revenue Service and the Federal Bureau of Investigation, but no one knew his whereabouts. Larson died of throat cancer on February 16,1999, in Apopka, Florida.