He found out while at the supermarket with his mother, John Ramsey told the Daily Beast in 2008.
"The headlines from a tabloid screamed out that Burke had done it," he said at the time.
The still-unsolved murder has haunted John Ramsey ever since, he said.
But the little girl's dad still believes the killer will be brought to justice.
Burke Ramsey files a $150 million defamation lawsuit against forensic pathologist Dr. The lawsuit stems from the airing of a two-part CBS docuseries about the murder of Jon Benét, in which Spitz theorized that Burke Ramsey killed his sister (CNN Fast Facts).