cbs news ` face the nation ' moderator bob schieffer announced wednesday at the texas journalism school named for him that he 'll be retiring this summer .
schieffer is a former newspaper reporter at the fort worth star-telegram .
he joined cbs news in 1969 and has been the network 's chief washington correspondent since 1992 .
he began at the political affairs show ` face the nation ' in 1991 , asking direct questions to politicians in a texas twang .
covered the assassination of jfk and 11 presidential campaigns - dating back to richard nixon .