Weber County, Utah, prosecutor Dee Smith said Monday an arrest warrant states Gregory Seamons, 15 at the time of the crime, was the person who killed Rebecca Lemberger, last seen walking to her elementary school in Ogden, Utah, in 1983, The Salt Lake Tribune in Salt Lake City reported Tuesday.
Smith lauded police detectives in Ogden for solving the 29-year-old cold case.
The warrant states DNA from the crime scene, a wooden shed where the girl was found with head injuries under a mattress by young classmates matched a DNA sample taken from Seamons.
Evidence collected from the scene also indicated the victim had been raped, the newspaper said.
Seamons, now 44, is imprisoned for a second-degree kidnapping conviction, the Idaho Department of Corrections website said.