A report on the Tucson shootings includes excerpts from Barbara Walters interviews with John Lennon's assassin, Mark Chapman; and the parents of John Hinckley, who shot President Reagan. Also: Brian Ross probes rapes of female Peace Corps volunteers and the 2009 murder of a volunteer in Benin; Ron Reagan Jr. recalls his father and discusses his relationship with him (President Reagan was born Feb. 6, 1911).