In 1979 a family hunting arrowheads in an Idaho cave found a headless torso in a shallow grave. In 2019, genetic genealogy gave it a name: Joseph Henry Loveless, a bootlegger who sawed his way out of a county jail in 1916 while accused of killing his wife with an axe. That case opens this episode on cold cases, investigations no longer actively pursued but never closed, which are mostly murders because murder carries no statute of limitations in the United States.

Cases freeze for human reasons, above all tunnel vision, when detectives fix on one suspect and stop seeing anything else. They thaw for other reasons. The BTK killer, Dennis Rader, mailed police a floppy disk without understanding metadata. The Golden State Killer was found through distant cousins on a public genealogy site. The episode also covers DNA that freed two wrongly convicted men, CIA drug experiments hidden for decades, and a former concentration camp guard deported 75 years after his crimes.

• Rader asked police through a classified ad whether a floppy disk could be traced. They said no, and the disk led to a user named Dennis at Christ Lutheran Church.
• In 2018 investigators uploaded crime scene DNA to GEDmatch, built family trees back to the 1800s, and arrived at Joseph James DeAngelo, a former police officer.
• Rolando Cruz and Alejandro Hernandez spent years in prison for the 1983 murder of ten-year-old Jeanine Nicarico before DNA matched Brian Dugan.
• In 1953 Harold Blauer died after an injection of a mescaline derivative, and Frank Olson fell from a hotel window nine days after being secretly given LSD.
• Friedrich Karl Berger, aged 95 and living in Tennessee, was ordered removed in 2020 for serving as an armed guard at a Neuengamme subcamp in 1945.