Around 11 a.m. on Dec. 2nd, 2011, 23-year-old Shawn Dickerson left his San Francisco house in a hurry -- his roommate and friend, Anjuli, thought he was late for work at Rolo, a men's clothing store. But rather than going to work, it appears that Shawn went for a walk around town, taking a series of photos to chronicle his day. The photos were uploaded to his Facebook page. These photos are the last trace of Shawn Dickerson.

In today's episode, we speak at length with Shawn's mother, Trisha Brucker. She shares with us the details of Shawn's disappearance -- and the hopes that he may still be alive.