(CNN) -- The former lead investigator in the JonBenet Ramsey case says that newly released documents may spark renewed interest, but they have little effect on the cold case investigation.
Previously sealed court documents released Friday show that a Colorado grand jury voted in 1999 to indict the parents of the slain 6-year-old JonBenet on charges of child abuse resulting in death and being accessories to a crime.
The district attorney decided that year, however, not to file charges against John and Patricia Ramsey, saying there was insufficient evidence. In 2008, a new district attorney said new DNA evidence cleared the parents and their son in the death.
The case has never been solved, and the released documents have put the killing back in the spotlight. But attention does not necessarily translate into leads in the case, former lead investigator A. James Kolar told CNN.
"It is unlikely unless there is a confession, or somebody else comes forward that has information that has been shared with them," he said.
Kolar wrote a book about JonBenet's killing and said he does not believe that there was an intruder at the Ramsey house that night, implying that the Ramsey family -- the late Patricia Ramsey, her husband John and their son Burke -- know more than they have told.
What exactly was it that kept the district attorney from pursuing the charges?
"That's a very complicated question. I think there are a lot of things that could be considered missing from the D.A.'s perspective to be able to bring them to a threshold of prosecuting beyond a reasonable doubt," Kolar said.
Still, the documents released Friday are an important part of the history of the case.
A Colorado court ordered the release of the previously sealed court documents about the unsolved 1996 death of the girl who won child beauty pageants and whose murder shocked the nation. The pages were sealed in 1999, after the grand jury in the case dispersed without charges being filed.
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