An author who has researched the Cold War's most famous espionage case said new evidence suggests another U.S. diplomat, not Alger Hiss, was the Soviet agent who fed U.S. secrets to Moscow.

The claim was presented Thursday at a daylong symposium, "Alger Hiss & History," at New York University. It provided new information that, if true, could point toward a posthumous vindication of Hiss, who was accused of spying for the Soviet Union and spent nearly five years in prison for perjury before his death in 1996 at age 92.

Also at the conference, a stepson of Hiss argued that Hiss' chief accuser invented the spy allegations after his sexual advances were rejected.

Author Kai Bird said there was new evidence to suggest that the real spy was another U.S. official named Wilder Foote. Hiss was accused of feeding secrets to the Soviet military intelligence agency GRU under the code name Ales.

Bird said he and co-researcher Svetlana A. Chervonnaya had identified nine possible suspects among U.S. State Department officials present at the U.S.-Soviet Yalta conference in 1945. A process of elimination based on their subsequent travels to Moscow and Mexico City excluded eight of them, including Hiss, he said.

"It left only one man standing: Wilder Foote," Bird said.