Bill O'Reilly

This Oct. 13, 2012 file photo shows Fox News commentator and author Bill O'Reilly at the Comedy Central "Night Of Too Many Stars: America Comes Together For Autism Programs" at the Beacon Theatre in New York.

(Frank Micelotta | Inivision via The Associated Press)

Questions over his reporting from the 1982 riot in Buenos Aires may be just the tip of the iceberg for Fox News' Bill O'Reilly. The embattled "O'Reilly Factor" host is facing new allegations of embellishing his connection to a key moment in the investigation of the assassination of President John F. Kennedy.

A new report from liberal watchdog Media Matters has gathered evidence against O'Reilly's oft-repeated claim that he was present during the suicide of Russian émigré George de Mohrenschildt, a friend of Kennedy's assassin Lee Harvey Oswald.

According to O'Reilly's account of the events of March 29, 1977 in his best-selling non-fiction book "Killing Kennedy," he was at de Mohrenschildt's daughter's home in Florida when the man shot himself with a 20-gauge shotgun.

He writes that a "reporter knocked on the door of de Mohrenschildt's daughter's home, he heard the shotgun blast that marked the suicide of the Russian ... that reporter's name is Bill O'Reilly."

O'Reilly has repeated this story several times over the years while promoting his book and the Fox News movie special based on it.

At the time, O'Reilly was a reporter for WFAA-TV in Dallas, and two of his former colleagues claim that he inserted himself into the story after the fact, and could not have been there at the time.

"He was not up on the porch when he heard the gunshots, he was in Dallas. He wasn't traveling at that time," Tracy Rowlett, a reporter colleague of O'Reilly's at WFAA, told Media Matters. "I don't remember O'Reilly claiming that he was there. That came later, that must have been a brain surge when he was writing the book."

Byron Harris, a reporter at WFAA for the past 40 years, also said O'Reilly was in Dallas at the time, and that if he had been there, WFAA would have reported the story as an exclusive item.

"He stole that article out of the newspaper," Harris said. "I guarantee Channel 8 didn't send him to Florida to do that story because it was a newspaper story, it was broken by the Dallas Morning News."

Aside from the word of two former colleagues, Media Matters report cites a Palm Beach County Sherrif's Office investigation into de Mohrenschildt's suicide which makes no mention of O'Reilly, and an Associated Press report from the time that states the only people at the home beside de Mohrenschildt were two maids, who did not report hearing a gunshot.

Media Matters report also refers to the 1993 autobiography of Gaeton Fonzi, an investigative journalist who reported relentlessly on the Kennedy assassination. In the autobiography, Fonzi seems to indicate that O'Reilly had no first hand knowledge of the suicide:

Further evidence against O'Reilly was collected by Jefferson Morley, a former editor for The Washington Post, in a post on his website jfkfacts.org.

Morley obtained phone conversations between Fonzi and O'Reilly on March 29, 1977, which, the editor writes, show that O'Reilly "certainly did not hear de Mohrenschildt's demise with his own ears. When the fatal shot rang out, O'Reilly was in his office at the WFAA studios in Dallas, Texas, more than 1,200 miles away."

At the end of the series of calls, O'Reilly says, "I'm coming down there tomorrow. I'm coming to Florida."

The new accusations against O'Reilly come as the Fox News host is embroiled in a furious battle against Mother Jones magazine's allegations that he claimed to have acted heroically in a Falklands War "combat zone" when in fact he was covering a riot in Buenos Aires.

Seven of O'Reilly's former colleagues at CBS have disputed his claim of rescuing a cameraman who had been knocked to the ground, among other contentious reports.

The allegations of embellishing reports came just weeks after NBC suspended veteran anchor Brian Williams for lying in his story about coming under fire while in a helicopter in Iraq in 2003.