After over 20 years of mystery, the identity of a man who died in Phoenix in 2004 has been confirmed as John Thiellesen, thanks to advanced genealogy techniques. Found unconscious on the street and later dying from heat exposure, his identity remained unknown despite conventional identification efforts. A breakthrough occurred when a blood sample was analyzed by specialized labs, leading to the discovery of living relatives, showcasing the potential of investigative genetic genealogy in solving missing persons cases.