In the run up to the Blue Rock Springs attack, Michael Mageau "stated that Dea came over at approximately 11:30 pm or shortly thereafter and picked him up in her car". Michael went on to say they headed in the direction of Mr Ed's along Springs Road before turning around and heading eastward toward Blue Rock Springs Park. Michael Mageau resided at 864 Beechwood Avenue and Darlene Ferrin at 1300 Virginia Street, both in Vallejo. However, further on in the report it states that Dean Ferrin (Darlene's husband) and Bill Lee (Darlene's employer) recounted that "Darlene and her sister Christina Suennen had been at Mr Ferrin's place of employment 'Ceasers' 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." Then, at "approximately 11:30 pm Lee called Darlene to ask her if she would try to find a fireworks booth open and purchase some as they were going to have a party at 1300 Virginia Street".
In combination with this, Pamela and Janet, who were babysitting for Darlene, stated that "Darlene didn't return until about 11:30 pm or shortly before that", and after a few minutes cleaning up the house she was going out to buy fireworks, "Darlene left the house around 11:40 pm and they didn't see her again". It was clear by the accounts of several people that Darlene was still at 1300 Virginia Street at 11:30 pm, and left approximately 10 minutes later, to arrive at Michael Mageau's Beechwood residence "shortly thereafter".
This places the couple entering the parking lot at 11:53 pm. We now have three independent statements to factor in the events hereafter, starting with Michael Mageau. Michael stated "they were there just a very short time, a few minutes, and three cars pulled into the parking lot where they were. They were apparently young kids and they heard some laughing and carrying on and a few firecrackers were set off, then the three vehicles left within a short time. Shortly after this and about 5 minutes before the shooting occurred, Michael states a vehicle pulled into the lot, coming from the direction of Springs Road and Vallejo. The driver turned the lights off on the car and pulled around to the left or east side side of their car, approximately six or eight feet away and sat there for a minute. The car drove off and headed in the direction of Vallejo and Springs Road. He stated approximately 5 minutes later it returned". The killer then approached the Corvair.
Deconstructing these statements and estimating the kids arriving after the couple by "a few minutes", considering the kids stayed to laugh and joke (and let off some firecrackers), we can place a minimum of 3 minutes on this duration. Michael stated after the kids left it was about 5 minutes before the shooting. Combining these two estimations puts the duration at 8 minutes, indicating that if they arrived at the parking lot at 11:53 pm, the time would now be 12:01 am on the 5th of July. However, Michael also stated that after the kids left a vehicle pulled up behind them, "sat there for a minute and returned approximately 5 minutes later", thereby extending the timeline to 6 minutes. This, coupled with a minimum of 3 minutes for the kids arriving and leaving, totals 9 minutes, thereby extending the time of the shooting to 12:02 am. All the timelines above are conservative estimates, so the 12:02 am calculation could equally be as late as 12:04 am. To verify or back up this prediction we shall now examine some further statements.
In the police report it chronicles three other people, Jerry, Roger and Debbie, who were heading along Columbus Parkway, entering the area of Blue Rock Springs from the northwest:. "it was dark and they looked for any vehicles. The only one they saw was the victims brown Corvair". They approached Mageau, wounded on the floor, and left to get help. "Both boys had to guess the time they were at the park as real close to midnight, possibly a little before midnight." However, it was likely slightly after midnight as we shall estimate. At approximately 12:10 am, Richard Hoffman "copied a radio message from KMA 818 regarding two teenagers being shot at in the area of Blue Rock Springs, R.O. had just checked this approximately 15 minutes prior to this transmission, and found the parking lot of Blue Rock Springs clear of people or motor vehicles". This statement uses approximation, because as we can see, 15 minutes prior to 12:10 am is 11:55 pm, and Michael Mageau and Darlene Ferrin pulled into the parking lot at around 11:53 pm, meaning they would have been spotted by Richard Hoffman. However, what it does tell us, is that Richard Hoffman likely missed the couple's arrival by a matter of minutes, probably passing the parking lot just prior to 11:53 pm.
The three youths, Debbie, Jerry and Roger, after seeing Michael Mageau pleading for help, set off to Jerry's home at 938 Catlewood Drive, Vallejo and subsequently called police. The time to reach 938 Castlewood Drive from Blue Rock Springs Park is about 6 to 7 minutes. We have estimated the shooting at 12:02 am. So Jerry, Debbie and Roger likely arrived at 12:03 am to 12:04 am, immediately after the shooting. The 6 minutes to arrive home and call police tallies nicely with the 12:10 am call by Debbie to dispatcher Nancy Slover and the transmission to Richard Hoffman.
With all the time periods above, a conservative approach has been adopted, implying the double shooting may have occurred slightly later - but from the phone call to the police and dispatch times, 12:04 am is the latest cut off point. The most likely time of the attack can be narrowed to 12:02-12:03 am on July 5th 1969. Although, the Zodiac Killer having begun the night with murder on his mind was clearly content with "On the 4th of July I did not open the car door. The window was rolled down all ready. The boy was origionaly sitting in the front seat when I began fireing". Debut of Zodiac Letter-August 4th 1969.