John Ramsey and his late wife have been cleared of suspicion in the death of their 6-year-old daughter JonBenet more than 11 years ago, the Boulder County, Colo., District Attorney's Office said.
In a letter to John Ramsey, district attorney Mary Lacy said that newly discovered DNA evidence did not match any member of the Ramsey family.
"We do not consider your family including you, your wife, Patsy, and your son, Burke, to be under any suspicion in the commission of this crime," the letter says.
Lacy then apologized to the Ramseys, who have long been under "an umbrella of suspicion," she said.
"To the extent that this office has added to the distress suffered by the Ramsey family at any time or to any degree, I offer my deepest apology," she said.
John Ramsey declined to comment, saying in an e-mail to ABC News, "I can tell you that I am grateful for the real professionals in the Colorado law enforcement community who continue to work quietly but effectively to find the killer of our daughter. I believe in my heart that someday we will."
Lacy's letter says investigators used a new form of DNA testing known as "touch DNA" to test the long johns that JonBenet was wearing when her body was found. She was murdered in the house where she lived with her family in late December 1996.
Analysts recovered DNA from the top portion of the long johns, on both sides, where the perpetrator may have put his hands. The new DNA samples match DNA that was recovered from the girl's panties in an earlier test.
Lacy said in a statement that the DNA belonged to the murderer, who has not been identified.
"The unexplained third party DNA on the clothing of the victim is very significant and powerful evidence," Lacy said. "It is very unlikely that there would be an innocent explanation for DNA found at three different locations on two separate items of clothing worn by the victim at the time of her murder."
John Ramsey's attorney did not immediately return a call for comment.
Patsy Ramsey died in 2006 of ovarian cancer.
ABC News' Beth Tribolet contributed to this report.