Sheriff's Deputy Russ Butterbach (assigned to the December 20th murders) indicated they were searching for clues to identify any possible link between the two cases. Sergeant Lawrence Kramer pointed out that different weapons were used in the Friday murders on December 20th 1968 and January 3rd 1969, but unbeknownst to him, this was to become a feature in all four of the canonical Zodiac attacks. Three days after the murder, on January 6th 1969, an abandoned foreign vehicle containing shotgun shells was found parked on Columbus Parkway in Vallejo. The registered owner was traced to Berkeley This location, on Columbus Parkway, would become the setting for the Zodiac Killer's second attack on July 5th 1969, when just after midnight, Michael Mageau and Darlene Ferrin were shot multiple times in their vehicle in a parking lot at Blue Rock Springs.
Darlene Ferrin (22) lived at 1300 Virginia Street, Vallejo, and was working as a waitress at Terry's Waffle Shop at the time of her murder, situated on Magazine Street, Vallejo, just off Interstate 80. The Waffle Shop and tavern were in close proximity to one another, on the same street.