"I know he didn't see it and nobody saw it and anyone who knew about that incident would have known they were killed in secret," said Scott Greathead, one of the lawyers representing relatives of the nuns during the prosecution of the killers.
"To use the death of four women who were in El Salvador just to do good for your own self-aggrandizement is unsavory," another lawyer who worked with the families told Media Matters, calling O'Reilly's remarks "disgusting" and "reprehensible."
The statements were the latest fallout after a report by Media Matters cast doubt on the Fox host's previous claims to have witnessed murders of the nuns as a reporter.
O'Reilly said he "saw nuns get shot in the back of the head" on his show "The O'Reilly Factor" in 2012, and that he had "seen guys gun down nuns in El Salvador" on his radio show in 2005.
Contrary to those statements, O'Reilly also said in 2009 that he arrived in the country after the nuns were massacred.
After the report was published, O'Reilly told Mediaite that what he meant was that he had seen photos of nuns being killed, not that he had witnessed them himself.
“While in El Salvador, reporters were shown horrendous images of violence that were never broadcast, including depictions of nuns who were murdered," he told Mediaite.
O'Reilly elsewhere claimed to have "seen" lethal bombings in Northern Ireland. A Fox News spokesman later clarified that again, O'Reilly had only seen photos of the killings in question.