The newspaper article stated "He was immediately advised of his rights concerning any statements he may make and legal representation to which he is entitled, the detectives said. Werner was then taken to the scenes of the crimes. Late yesterday he was undergoing questioning. The detectives would not reveal what statements, if any, he had made concerning the killings of the three girls". The Zodiac Killer would respond in his decoded letter to the San Francisco Chronicle, warning the police "Tis the Zodiac Speacking. Why can't you stop me. I can't stop killing. Stop listening t(o) phonys. If this is not on your front page in a week I will skin 3 little kids and make a suit from the skin" (coded section).
He was effectively saying to police who were questioning Karl Werner "stop listening to this phony (impostor, fraud). I am the real killer". In view of the title of this article 'San Jose Student Held in Slaying of Three Girls', it probably isn't too surprising he threatened a further "three little kids" if they didn't print this letter and cipher on their front page.
He also wrote on the '148 Character' cipher letter "Next time I will send a patch of skin if their is some left over". Bearing in mind the 200+ stab wounds these young girls suffered, this statement doesn't require much explanation.
Both the Monticello card and '148 Character' cipher inferred a total of 21 victims, suggesting they were authored by the same individual.