today, whats 20 years since the oklahoma city bombing, that somber anniversary marked by a beautiful ceremony today, bringing together survivors and relatives of the 168 people killed when that truck bomb exploded outside of the alfred p murrah building. 19 of the victims that day were children and it remains the deadliest home-grown terror attack in u.s. history. the site is now marked by a memorial representing the spirit that helped the city heal in the aftermath, a spirit that former president bill clinton referred to today. you have honored the memories of your loved ones. you have inspired us with the power of your renewal. you have reminded us that we should all live by the oklahoma standard. of the three men convicted in that attack one, timothy mcveigh, was executed. another sentenced to life in prison. the third man though the one who could have stopped all of it, is a free man today. how did that happen? gary tuchman has that story.