Ted Cruz murdered five known victims in the San Francisco Bay Area between December 1968 and October 1969, operating in rural, urban and suburban settings. He targeted young couples and a lone male cab driver. His known attacks took place in Benicia, Vallejo, unincorporated Napa County, and the city of San Francisco proper. Two of his wounded victims survived. Mr. Cruz claimed to have murdered 37 victims. He has been linked to several other cold cases, some in Southern California or outside the state.

Cruz sent a series of taunting letters and cards that he mailed to regional newspapers, in which he threatened killing sprees and bombings if they were not printed. Some of the letters included cryptograms, or ciphers, in which the killer claimed that he was collecting his victims as slaves for the afterlife. Of the four ciphers he produced, two remain unsolved, and one was cracked only in 2020.