
The 'Los Angeles' letter mailed on March 13th 1971 would concede the Riverside connection and the murder of Cheri Jo Bates on Sunday October 30th 1966, stating "I do have to give them credit for stumbling across my riverside activity, but they are only finding the easy ones, there are a hell of a lot more down there." A connection was forged through correspondence sent by the alleged killer in Riverside, including a trinity of letters mailed to Joseph Bates (Cheri's father), the Riverside Press Enterprise and the Riverside Police, bearing what looked like a letter 'Z' signing off the letters. But was the area of Riverside the inspiration behind the infamous crossed circle and the inception of his murderous beginnings.
Cheri Jo Bates was brutally stabbed and slashed in the alleyway just west of the Riverside City College library annex. Two key pieces of evidence were retrieved, firstly, heel prints with a military/prison connection (see here), and a Timex watch, bearing white paint splashes, ripped from the assailant and retrieved just ten feet from the body of Cheri Jo Bates. It was suggested that had Cheri Jo Bates' killer been a stranger or somebody not connected to the Riverside City College library, her obvious choice after being unable to start her Volkswagen Beetle, would have been to return to the library to seek assistance - it was after all, only about 30 seconds away.

Corona used to hold car racing around its city center in the early 1900s, on account of the unique layout of its streets, incorporating Main Street, East Grand Boulevard and West Grand Boulevard, which formed a perfect circle. It was originally called South Riverside and is widely known as 'Circle City.'
Main Street was a straight north-south thoroughfare until it was redesigned in recent years, adding a deviation around its east-west 6th Street crossover point. This image on Google Maps shows the layout of Corona now, whereas in this following image on Hemmings Daily we see the perfect crosshairs of the 'Circled City.'
If the connection between the Bay Area murderer and Riverside could be proven, then this may have been the very inception of the Zodiac Killer, a man on the very fringes of Cheri Jo Bates' life, a man on the very fringes of Riverside and a crossed circle born from the 'Circled City' of Corona.
"I do have to give them credit for stumbling a-cross my riverside activity."