The Zodiac Killer

Two days later, the Chronicle received a letter from the Zodiac claiming responsibility for the murder.  The return address on the envelope was the crossed-circle design, and enclosed with the letter was a swatch of Paul Stine's bloody shirt.  Three latent fingerprints were developed on the paper by the SFPD crime lab, but remain unmatched to any suspect.

This is the Zodiac speaking.  I am the murderer of the taxi driver over by Washington St + Maple St last night, to prove this here is a blood stained piece of his shirt. I am the same man who did in the people in the north bay area. The S.F. Police could have caught me last night if they had searched the park properly instead of holding road races with their motorcicles seeing who could make the most noise. The car drivers should have just parked their cars and sat there quietly waiting for me to come out of cover. School children make nice targets, I think I shall wipe out a school bus some morning. Just shoot out the frunt tire + then pick off the kiddies as they come bouncing out.

The Zodiac would send three swatches of the bloody fabric, but 104 square inches of Paul Stine's shirt are still unaccounted for.

Thus far, authorities had observed the Zodiac to follow a few vague patterns. He had always attacked after sundown on weekends, always attacked young couples in or near their cars, and always attacked in remote suburban areas near water. If he could now break his pattern by shooting a lone 29-year-old male in downtown San Francisco, they felt, then there was no reason why he couldn't follow through on his threat to "wipe out a school bus;" within days, Bay area bus drivers had received special instructions on how to react if fired upon.

The school bus threat was one that the Zodiac would return to in different forms.  At the urging of the San Francisco Police, the Chronicle suppressed the threat for a week; on October 18, a police composite sketch based on the teenage witnesses' testimony was amended according to the descriptions given by the responding patrolmen at Cherry Street and was distributed with the full content of the letter.

It was during this time that the Zodiac case began to garner exceptional press coverage, and tips to the killer's identity poured in from points as far as Houston, Atlanta, and St. Louis.  At the same time, homicide detectives along the West Coast began to consider the Bay Area killer as a suspect in their unsolved cases.  Among these were L.T. Kinkead and H.L. Homsher of the Riverside, CA, Police Department, and they forwarded a summary of the 1966 Bates murder to investigators in Napa, Solano, and San Francisco Counties. ¹  The summary was lost in the shuffle for over a year.