US TV star Savannah Guthrie's 84-year-old mother Nancy has been missing for 12 days, with authorities investigating thousands of leads including a pair of gloves found near her home. Over 18,000 tips have been submitted to investigators, with 4,000 coming in the 24 hours after CCTV footage was shared publicly. Retired FBI Special Agent Richard Kolko explains how law enforcement agencies prioritise and process the massive volume of tips while working to find Nancy alive.