The son of a Kansas law enforcement officer who helped investigate the 1959 killings that inspired the book "In Cold Blood" can publish his father's field notes that he says substantially contradict the account found in Truman Capote's literary masterpiece.

In a ruling made public Monday, Shawnee County District Court Judge Larry Hendricks said he made an error when he initially blocked publication of the criminal investigation files in 2012. His decision means that Ronald Nye of Oklahoma City can use his father's files for a book he plans about the slayings of prominent farmer and community leader Herbert Clutter, his wife and two children in Holcomb.

The Kansas attorney general's office had sued Nye to keep him from publishing the files. Nye had planned to auction the records, but later decided to write a book with author Gary McAvoy. Nye and McAvoy can now work with agents and find a publisher for their book.

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Nye's father, Kansas Bureau of Investigation agent Harold Nye, kept the case files at his home. Hendricks ruled Nye's First Amendment right to publish the material outweigh the government's interest in maintaining the confidentiality of its investigative records. Nye and McAvoy would not reveal exactly what is in the files, but Nye said Monday that his father's notebooks had "vast discrepancies" from what Capote wrote.

"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," McAvoy said. "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."

The state's lawsuit also asked the court to decide legal ownership of the case files. The judge has made no ruling on that issue.

Kansas Attorney General Derek Schmidt's office did not respond to email and phone messages seeking comment Monday.

Clutter; his wife, Bonnie Mae Fox; and their children, 15-year-old Kenyon and 16-year-old Nancy, were killed at their rural farmhouse. The hunt for their killers mesmerized the nation, drawing journalists from across the U.S. to the small, western Kansas town. Parolees Dick Hickock and Perry Smith were executed for the killings in 1965.

Capote's book about the crime inspired a movie of the same name.

The judge wrote that Kansas had not shown a legal justification for suppressing the material or for interfering with the public's right to know what is in them. He also rejected the state's argument that the Clutter family's privacy concerns justified blocking their release.

"The court is sensitive to the plaintiff's concern about publicity and its effect on the Clutters," Hendricks wrote. "However, publicity continues to follow this case even 55 years after its occurrence."

O. Yale Lewis, Jr., an attorney for Nye and McAvoy, said his clients hope to have their book published in time for the 50th anniversary in September of the publication of Capote's book.

Ronald Nye said his late father took detailed notes about the case. Nye recalled that his father was so disappointed in Capote's book that he read only about 115 pages before throwing it across the room. He said his dad walked out of the movie's premiere after just 15 minutes.

Harold Nye worked for the Kansas bureau from 1955 until his retirement in 1975; he was its director from 1969 to 1971.

The state's lawsuit names as defendants Harold Nye's adult children, Ronald Nye and Terry Hurley; his widow, Joyce Nye; and McAvoy and his Seattle-based auction company, Vintage Memorabilia, which specializes in film and literature relics.