From what we are led to believe, the Zodiac Killer was apparently more cautious of the male, dispatching them first, before venting his hatred on the female victim. He shot Michael Mageau while he was effectively trapped in the confines of Darlene Ferrin's Corvair, kept his distance from Bryan Hartnell, ordering Cecelia Shepard to tie her companion securely, and blindsided Paul Stine, execution style from behind. This man is likely not afraid of the male, albeit, he is applying common sense in completing his mission without being disarmed or thwarted. The attack on David Faraday and Betty Lou Jensen was committed in near complete darkness. If we are to believe eyewitness James Owen, the Zodiac Killer didn't even park behind the Rambler to illuminate his prey.
Fortunately for the Zodiac Killer, he came prepared with a small pencil flashlight, in which the "center of the beam of light, if you aim it at a wall or ceiling you will see a black or darck spot in the center of the circle of light about 3 to 6 inches across. When taped to a gun barrel, the bullet will strike in the center of the black dot in the light."
What an extremely cunning move- that is- until you walk forward towards your victim- in this case David Faraday. The closer you get, the smaller the circle of illumination becomes. When you finally press the .22 caliber handgun to the left ear of David Faraday, the light has effectively become extinguished. The turnout has now, in essence, been plunged back into darkness. From a killer apparently wary of the male, this, on the face of it, appears rather a foolish choice under the circumstances experienced at Lake Herman Road that night. Why not just approach David Faraday and shoot him in the head from 2 or 3 feet away with your extremely accurate pencil flashlight. Why get within contact range and not only risk being disarmed, but lose a visual on Betty Lou Jensen? From a man who carefully crafted a 340 character cipher, took the time to construct a sighting implement for his nighttime weapon, and applied caution towards his intended male victims, this seems a rather odd choice to say the least. Unless, it didn't happen this way.
There was absolutely no need for the Zodiac Killer to negate the use of his 'claimed' pencil flashlight and make contact with David Faraday. He supposedly has them herded together just outside the open door of the Rambler, and cannot afford for them to be separated into the darkness. The idea of Betty Lou Jensen making a dash for freedom and being targeted accurately by Zodiac at least five times, while David Faraday is still alive and standing behind him, is extremely problematic and unlikely. Seemingly, David Faraday had moved little since being forced from the vehicle. He was found lying perpendicular to the Rambler, with his feet just shy of touching the rear right wheel. It appears he was shot, execution style in close proximity to the vehicle.
There is every indication, based upon the reasoning suggested, that the Zodiac Killer was not alone in the turnout that night- he had an accomplice. With two assailants, possibly goading one another into action, the idea of removing the couple from the Rambler is paradoxically not without reason. Why extricate the couple from the vehicle in near pitch darkness, when you have them exactly where you want them, just like at Blue Rock Springs Park. The Zodiac Killer had never taken liberties with his victims in any of his subsequent attacks.
Item  was removed from the brain of David Faraday.
If the bullet removed from David Faraday exhibited different class characteristics to all the others, then it may become problematic from the standpoint of a lone gunman.
If a left-handed, second assailant, had David Faraday secured around the neck alongside the Rambler for the duration of the attack on Betty Lou Jensen, with a gun pressed to his left ear, then the ejected cartridge case could be the one discovered on the front passenger floorboard of the Rambler by responding officers.
This cartridge case was missing from the D.O.J. report. If it was to be found, then the story of the Zodiac Killer could turn on its head.