Complex sentence: In the early 1990s, he began investigating and asserting that the 1963 Kennedy assassination, the 2002 death of Senator Paul Wellstone, and the 9/11 attacks resulted by government conspiracies.
Split into simpler sentences: In the early 1990s, he began investigating the 1963 Kennedy assassination, asserting that it was the result of a government conspiracy. He later said that the 2002 death of Senator Paul Wellstone, and the 9/11 attacks were also government conspiracies.