Investigators solve 1956 killings of Montana teens. It may be the oldest case cracked using DNA and forensic genealogy.

DNA evidence preserved after a 1956 double homicide and the use of forensic genealogy has helped a Montana sheriff's office close the books on the 65-year-old cold case, officials said.

Investigators with the Cascade County Sheriff's Office concluded Kenneth Gould - who died in Oregon County, Missouri, in 2007 - more than likely killed Patricia Kalitzke, 16, and Duane Bogle, 18, CBS affiliate KRTV reports. Both were shot in the head. Detective Sgt. Jon Kadner, who took over the case in 2012, said Tuesday it was the oldest case he could find nationwide that has been solved using forensic genealogy, which searches commercial DNA databases to find familial matches to the DNA of a crime suspect.