a star-studded send off for david letterman. the "late show" host retires from a career in comedy with a final show filled with laughs. >> i'll be honest with you, it's beginning to look like i'm not going to get ""the tonight show"." >>> a break in the case in a washington, d.c. family killed in their home. police are on the hunt for a suspect and prepared to charge him with four counts of murder. >>> the united states releases thousands of documents seized from osama bin laden's hideout, including what he was reading and future plans for al qaeda. this is the "cbs morning news" for thursday may 21st 2015. good morning. good to be with you. i'm anne-marie green. top ten list stupid pet tricks presidential interviews and celebrity encounters that often went off script. david letterman said good-bye to