When the killer is known to the victim, it certainly provides a greater opportunity to apprehend the responsible, as opposed to a completely random assailant. We will use the visual below, in conjunction with the estimated times in the police report, to pinpoint Darlene Ferrin's movements and what time she and Michael Mageau arrived at the Blue Rock Springs parking lot that night, and possibly explore where her murderer tagged onto her that night, if at all.
1.Page 19 of the police report "Stated that Darlene and her sister Christina Suennen WFJ 15 years. had been at Mr Ferrin's (Dean) place of employment Caesar's in the 300 Block of Tennessee Street at approximately 10.30 pm and at this time Darlene left, stating that she was going to take Christina home, then go home herself to 1300 Virginia Street. Take her babysitter home, and return home herself." Christina stated "she collaborated the above story, but stated she and her sister had gone from Caesar's to Terry's on Magazine St, before going home." Therefore she left Caesar's at approximately 10.30 pm, arriving at Terry's Waffle Shop nearly 3 miles away, approximately 6 minutes later at 10.36 pm.
2. We cannot be sure how long she stayed at the Waffle Shop, but according to Robert Graysmith she talked to her friend for around 10 minutes, before briefly chatting to a man. This can only be estimated at 15 minutes, which would have Darlene and Christina heading off to their parents home on 130 Jordan Street at 10.51 pm. This is a small journey time of approximately 3 minutes, arriving at the Suennen family home at 10.54 pm. We know from the police report that Darlene arrived home shortly before 11.30 pm, as can be seen on page 21. This can be corroborated by page 19 of the police report, because "at approximately 11.30 pm Bill Lee (Dean's employer at Caesar's) called Darlene to ask her if she would try to find a fireworks booth open. She stated she would try to find one and hung up." The journey from the Suennen family home to Darlene's residence of around 2.6 miles is estimated at 7 minutes.
3. Therefore, Darlene Ferrin likely stayed at the 130 Jordan Street residence for about 25 minutes, leaving at 11.18-11.20 pm for her 7 minute journey, having Darlene back at the 1300 Virginia Street residence shortly before 11.30 pm.
4. On page 21 of the police report the two girls stated "that Darlene didn't return until about 11.30 pm or shortly before that. Darlene then told them that she had changed her mind about going to San Francisco and was going to have a small party when her husband got home. Darlene then spent a few minutes cleaning up the house and then she said she was going to go out and buy some fireworks and other things for the party and that she would be back by 12.30 am. Darlene left the house around 11.40 pm and they didn't see her again." Darlene Ferrin left her residence and traveled to Michael Mageau's house at 864 Beechwood Avenue. On page 8 of the police report he stated "that Dea came over at approximately 11.30 pm or shortly thereafter and picked him up in her car." We know it wasn't 11.30 pm, because Bill Lee and the two girls stated otherwise- plus she still had the 2 mile journey to 864 Beechwood Avenue to negotiate. This journey time is 5 minutes, placing Darlene Ferrin at Michael Mageau's residence at 11.45 pm or thereabouts (11.40 pm plus 5 minutes).
5. Michael stated in the police report "they were both hungry as they had not had supper and were going to get something to eat. Stated that she was driving her vehicle, the Corvair they were found in. Stated they drove west on Springs Road and as they were driving down Springs Road to go get something to eat, Dea stated to him that she wanted to talk to him about something. Michael stated that at approximately at the location of Mr Ed's on Springs Road they turned around and headed east at his suggestion to go to Blue Rock Springs Park where they could talk. They went directly to this location." The journey from 864 Beechwood Avenue to approaching Mr Ed's Drive-In is about 2 minutes allowing for turning around. They would be turning around, heading back east at approximately 11.47 pm.
6 and 7. The journey from Mr Ed's to the parking lot at Blue Rock Springs Park of 3 miles takes approximately 6-7 minutes, placing Darlene Ferrin and Michael Mageau arriving at the parking lot in their brown Corvair at 11.53-11.54 pm.
We know from Michael's statement approximately 5 minutes elapsed between the first vehicle parking alongside them and supposedly returning to begin the attack. We know Michael allocated "a few minutes" from their arrival to the three cars arriving. He also allocated "a few minutes" to the duration the three vehicles remained in the parking lot. Taking this "few minutes" as about 3 minutes, we have a total of 6 minutes. Adding this to the 5 minutes the 'Zodiac' vehicle spent leaving and returning, we have a total of 11 minutes from their arrival at the parking lot to the commencement of the attack. This places the shooting of Michael Mageau and Darlene Ferrin at 12.04-12.05 am on July 5th 1969. Even if we take the "few minutes" as two, the earliest the attack could have began was 12.02-12.04 am- the earlier time of 12.02 am the most likely. It was extremely unlikely to have taken place before midnight.
This contradicts what Carmela Piccolo-Coakley, then co-owner of Caesar's restaurant, said to the Vallejo Times-Herald in 2007: "We were surprised when we all arrived at the house to find a babysitter. Darlene hadn't gotten home yet. It was midnight and we were a little worried. An hour or so later the phone rang but there was only breathing on the other end." This version of events, albeit in 2007, makes more sense than arriving at 1.30 am in the morning, when you have arranged for fireworks to be collected at 11.30 pm, and are expecting a party.
Darlene Ferrin traveling to Michael Mageau's residence and finally to Blue Rock Springs, suggested she had seemingly abandoned the party and chosen to do something completely different- but this may not necessarily be the case. Although earlier arranging to meet Michael Mageau at some point that evening, she may very well have recruited Michael Mageau in her quest to buy some fireworks, along with getting something to eat. She stated to the two girls "she would be back by 12.30 am." Therefore, she was allocating herself 60 minutes to pick up Michael, head off for a bite to eat, pick up some fireworks and then head home. There may have been something else on her shopping list that night, as revealed by the two girls on page 21 of the police report when they stated "she was going to go out and buy some fireworks and other things for the party." What were these "other things?" However, something changed abruptly on their approach to Mr Ed's Drive-In, that facilitated a change of heart. She stated "that she wanted to talk to Michael about something."
She picked Michael Mageau up at 11.45 pm and had ample time before reaching Mr Ed's to have relayed to Michael what was on her mind. They both apparently had wanted something to eat, and Darlene required fireworks, yet the "something" on her mind seemingly only occurred two minutes into their journey while approaching Mr Ed's. Had she spotted something or somebody that forced this change of plan- somebody unpleasant enough that she had now abandoned her wanting to eat, her search for fireworks and possibly the party. On the other hand, Michael Mageau and Darlene Ferrin had arrived at the parking lot of Blue Rock Springs at approximately 11.53-11.54 pm, so still had at least 36 minutes to have their chat and for Darlene to arrive back at the 1300 Virginia Street residence at 12.30 am, with or without the fireworks she said she would try to find, and more importantly the time she told the two girls she would arrive back earlier that night. Unfortunately though, she never did.