G. Gordon Liddy, a brash former FBI agent who helped orchestrate the 1972 Watergate break-in, a crime that began the unraveling of Richard Nixons presidency, died Tuesday at the age of 90, the Washington Post reported. Liddy, who parlayed his Watergate infamy into a 20-year career as a conservative talk-radio host, died at his daughters home in Fairfax County, Virginia, the paper said.