For years after the slaying, tabloids and crime shows went after the couple. News reports also cast suspicion on JonBenet's older brother, Burke, who was 9 when his sister was killed. Lacy's predecessor as district attorney, Alex Hunter, said in 1997 that the parents were under an "umbrella of suspicion."
"No innocent person should have to endure such an extensive trial in the court of public opinion, especially when public officials have not had sufficient evidence to initiate a trial in a court of law," Lacy wrote.
Early in the investigation police found male DNA in a drop of blood on JonBenet's underwear and determined it was not from anyone in her family, but Lacy said they were unable to say who it came from and whether that person was "innocent or otherwise."
Then late last year, prosecutors turned over long underwear JonBenet was wearing to the Bode Technology Group near Washington, which used a new technique called "touch DNA" to find previously undetected DNA evidence.
Touch DNA involves scraping genetic material that could not otherwise be seen. Two samples were found on the sides of her long underwear, in an area where an attacker would have pulled them down.
The results, reported to prosecutors in March, indicated the newly discovered DNA matched the DNA found earlier, and was not from the Ramsey family. Lacy said the presence of the same male DNA in three places on the girl's clothing convinced investigators it belonged to JonBenet's killer, and had not been left accidentally by an innocent party.
"It is therefore the position of the Boulder District Attorney's Office that this profile belongs to the perpetrator of the homicide," she wrote.
Lacy declined to comment through a spokeswoman.
Lacy has previously expressed doubts that the parents were involved. In 2003, a federal judge handling a defamation lawsuit in Atlanta involving the Ramseys said evidence in the case was more consistent with the theory that an intruder killed JonBenet, not her parents, and Lacy said she agreed.
John Ramsey found his daughter's strangled and bludgeoned body in the basement of the family's home in Boulder on Dec. 26, 1996. Patsy Ramsey said she found a ransom note demanding $118,000 for her daughter.
John Ramsey, a software entrepreneur, has said in interviews he believes the case will be solved.
Patsy Ramsey died June 24, 2006, of ovarian cancer at the age of 49 in Atlanta, where the family moved after JonBenet's death.
"My first thought was obviously I wish Patsy Ramsey was here with us to be able to at least share vindication of her family," said L. Lin Wood, an attorney for the Ramsey family.
"There are many people in this country, if not around the world, that also owe John and Patsy Ramsey and Burke Ramsey (their son) an apology," he said.
Less than two months after Patsy Ramsey died, the case appeared to blow wide open with the arrest in Thailand of John Mark Karr, a sometime teacher obsessed with the little girl's slaying. Karr made bizarre, detailed confessions to the killing, but authorities said DNA evidence showed Karr did not commit the crime.
Slideshow archive | ABC13 wireless | Help solve crimes