David Lane, a defense attorney not involved in the case, said prosecutors may have handed it over to grand jurors because problems in the investigation could have made it difficult to prosecute. But he said that could have backfired with a "runaway grand jury" that reached its own conclusions.
He said the indictments could have been an attempt to force the parents to turn against each other, which he said was unlikely because both were protected by laws that limit testimony of one spouse against another.
"Somebody killed JonBenet Ramsey," Lane said. "It sounds like they were accused of aiding and abetting each other, with the hope someone would crack and break. That didn't happen, and prosecutors may have decided not to go forward."
Although the grand jury foreman signed the 1999 indictments, prosecutors decided not to bring charges.
Christina Habas, a retired judge who oversaw grand juries in Denver, said it's at the discretion of the district attorney whether to file charges because prosecutors have to consider whether they can convince a trial jury of someone's guilt beyond a reasonable doubt.
The indictments might have been a compromise among jurors who were divided on what counts should be approved, said Nancy Leong, an assistant law professor at the University of Denver. The release of only four of 18 charging pages, and the numbering of the charges, suggest other possible charges were passed over. The charge of accessory to a crime might have been an attempt to "meet in the middle," Leong said.
"And that would also explain why the prosecutor didn't want to continue with the prosecution of the crime, because there might not have been enough evidence to prove the parents helped someone else cover up the crime," she said.
Whatever the motivation behind them, the documents add little or nothing to the public understanding of what happened to JonBenet, Leong said.
"We don't know much more factually, if anything, than we did in 1996," she said.
The Daily Camera newspaper in Boulder reported earlier this year that the grand jury had issued indictments, and the documents were released in response to a lawsuit filed by its reporter, Charlie Brennan, and the Reporters Committee for Freedom of the Press.
Associated Press writers Steven K. Paulson and Dan Elliott contributed to this report.