It was stated in the DOJ report that one of the eight bullets tested did not exhibit 6 right hand groove class characteristics. This was the bullet recovered from David Faraday. The casing from the bullet fired at David Faraday was likely ejected to the rear of the shooter and may well have been the casing found in the front passenger side floorboard of the Rambler. Since only nine casings were tested, it was conjectured that this tenth casing may have become separated from the other nine when the Rambler was towed away and therefore not sent to the DOJ.
If this casing exhibited different characteristics to the other nine, it may be related to the bullet taken from David Faraday at autopsy, which did not exhibit the same characteristics as the other seven bullets recovered and possibly indicate a second firearm was used at Lake Herman Road. The problem is tracking down the missing casing.
This is explained in more detail here;
"STATE OF CALIFORNIA
OFFICE OF THE ATTORNEY GENERAL
DEPARTMENT OF JUSTICE
PO BOX 944255
SACRAMENTO, CA 94244-2550"
RE: Zodiac Killer
Dear Mr. Raymond Grant:
Thank you for your correspondence to the Office of the Attorney General requesting that a crime involving the Zodiac Killer be investigated and that the alleged perpetrator of the crime be prosecuted.
If you have information about a crime, please file a report with the police or sheriff's department in the area where the crime occurred. Local law enforcement authorities are responsible for investigating violations of law within their jurisdictions. After investigating the crime, the local law enforcement authorities may forward the case to the county district attorney's office for prosecution, if appropriate. The decision whether or not to file criminal charges will then be made by the locally elected district attorney. In this matter, we suggest that you contact:
San Francisco Police Department
850 Bryant St., Room 525
Telephone: (415) 553-1484
But as Ray said "The most discouraging aspect of the letter is that they explained that the investigation was a jurisdictional matter, but got the jurisdiction for the specific crime wrong. The Lake Herman Road murders are under the jurisdiction of the Solano County Sheriff's Office. In any case, it's a dead end, because the physical evidence, if it still exists, would be warehoused by the DOJ and not by Solano County SO, which would just respond to any inquiry by saying that it doesn't have possession of the evidence, and that you should probably contact the CA DOJ." Edited.
The missing casing will not reveal who killed David Faraday and Betty Lou Jensen, but it may reveal whether it was one killer or more than one killer. For now though, it's another dead end.