In Cold Blood has been regarded as a masterpiece by many lit lovers over the years, and Truman Capote’s telling of the violent real-life murders of the Clutter family in 1959 was turned into an award-winning film in 2005, which renewed interest in the family’s story. But now, a judge has revealed that he believes he made an error when he kept files from the criminal investigation from being published in 2012. Those files are partially made up of field notes from Harold Nye of the Kansas Bureau of Investigation, and Nye’s son, Ronald, is planning a book based on the information within.

Nye plans to write the book with author Gary McAvoy, who says they believe the information contained in those files contradicts Capote’s story.

“Our belief is that there is no other reason (Kansas) would want the materials we have suppressed were it not for the information we found in them. That information connects to other research I’ve done and supports a pretty compelling new theory, one that I am reluctant to even discuss at this point,” McAvoy said.

While it’s not clear what’s in the files, Nye says his late father was very upset by Capote’s account of the murders and couldn’t bring himself to finish the book. District Court Judge Larry Hendricks said that he kept the information from being released to the public because of continued interest in the case, citing a concern for the Clutter family’s relatives.

Herbert Clutter, his wife, Bonnie Mae Fox, and their children, 15-year-old Kenyon and 16-year-old Nancy, were brutally murdered in their home. The search for their killers left the country stunned and in fear for their own lives, as many wondered how they could be safe when a well-respected family from a rural community had been targeted. Finally, in 1965, Dick Hickock and Perry Smith were executed for the deaths.

Nye and McAvoy are reportedly looking for a publisher for their book.