In 2004, NFL football star-turned-Army Ranger Pat Tillman was killed in Afghanistan. While the Pentagon initially said Pat Tillman died heroically in an enemy ambush, the military later disclosed what it knew all along: Pat Tillman was shot and killed by his fellow soldiers. Today, his mother Mary says she still doesn't have the full story of how her son died. She's written a new book about her search for answers, "Boots on the Ground by Dusk: My Tribute to Pat Tillman," which she recently discussed at the Commonwealth Club of California.