On April 30, 1967, exactly six months after the Bates murder, Bates' father Joseph, the Press-Enterprise, and the Riverside police all received nearly identical letters: in a handwritten scrawl the Press-Enterprise and police copies read "Bates had to die there will be more", with a small scribble at the bottom that resembled the letter Z. Joseph Bates' copy read "She had to die there will be more", this time without the Z signature.[51] On March 13, 1971, five months after Avery's article linking the Zodiac to the Riverside murder, the Zodiac mailed a letter to the Los Angeles Times. In the letter he credited the police, instead of Avery, for discovering his "Riverside activity, but they are only finding the easy ones, there are a hell of a lot more down there."[52]