In 1924, two climbers named Andrew Irvine and George Mallory died atop Mount Everest. Neither of their bodies was ever found, and the cause of their deaths has remained a mystery. The NOVA: Lost on Everest project seeks to find Irvine and Mallory and identify their remains by DNA profiling. Even after more than seventy-five years, DNA profiles should be possible. This interview with DNA lab technician Gill Rysiecki tells how.