diane holik. whose friends came together to remember how they miss her. even after all these years. >> she was a constant friend. she was in my life every day and all of a sudden she was gone in an instant like blowing a candle out. >> you see the smile on all these photographs. was she always smiling? >> always. always. >> she had a magic smile. it was infectious. if she was smiling everybody else had to. we had to. i'm andrea canning, and this is "dateline." andrea canning: it was one of the most harrowing days in our history. >>> i hear this pop, pop, pop,. the attempted assassination of president reagan. >> screaming and yelling. it is chaos. >> and now unprecedented look into the mind of the gunman, john hinckley junior. and the police officer that questioned hinckley speaks out in his first television interview. >> he turned to her and said, will you marry me? >> secrets of his diaries on daylight. his obsession to actress jody foster. is hinckley really fit to be free. >> he's a potentially dangerous character. he's proven that. >>> hello. welcome