Home Alone

Verhaal

Allison Feldman was a young woman living in Scottsdale, Arizona, whose life appeared to be taking off. Her career as a medical salesperson was thriving; she had a steady boyfriend, a loving family and a wide circle of friends. That all changed one evening in February of 2015 when Allison was found brutally beaten and sexually assaulted inside her home. Detectives interviewed the people closest to her, but none matched the most critical evidence: a clear, unknown DNA profile recovered from the crime scene. Allison's murder remained unsolved for years until advances in forensic familial DNA pointed investigators to a man with no known connection to Allison who held the clues to crack the case wide open.  "20/20" contributors David and Kristen Mittelman of Othram Labs, one of the country's preeminent forensics labs, share insight into how familial DNA works and how this crucial DNA evidence helped catch a killer.