I have always said that in my opinion, given the top 4 or 5 suspects we had to choose from (Allen, Marshall, Kane, Gaikowski etc) that Kane the most likely, in my opinion at least, to be Z. But this was before really knew anything of James Owen as a suspect. I have been seen as another amateur sleuth with a pet suspect and will hear nothing to the contrary and that's never been accurate. I have tried to remain objective and in light of discovering all that James Owen said and did in relation to Lake Herman Rd, I would even say he is more likely responsible that any other suspect and that is including, Larry Kane!
When a homicide is committed, Detectives main priority is to establish two things. Who was the last person to see the victims alive? And who has both motive and opportunity?
Well, The offender responsible for The Lake Herman Road Double Homicide can be flushed out using Arthur Conan Doyle famous logic that: "Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth"
We know that witnesses (Peggy & Homer) report seeing Bettye and David alive and well as late as 11.15. At 11.20, James Owen 'passes' the scene. At approx. 11.25 - Stella Borges approaches the scene and discovers the bodies of Betty Lou and David sprawled on the gravel of the pumping station entrance. Stella Borges states that from starting out on Lake Herman, rite up to the locations where she discovered the two victims, no other vehicle passed her heading the other way. So, putting Owen's claims of a innocent passing vehicle going passed him aside, The Offender, Zodiac, could not have left the scene in a vehicle and headed toward Vallejo. The offender must have shot the two at the gated entrance then proceeded toward Benicia, which, as it happens, is the direction Owen was travelling. Responding officers coming from both directions recall passing no other vehicles while speeding to the scene. So, given the timeline and window of opportunity that Zodiac has in this instance and by a process of elimination, only Owen can be placed at the scene at or extremely near the time the two were killed, so he has the opportunity. Motive? Owen has no motive to slaughter these two teens specifically because its not personal. The Motive for the crime itself, knowing now who's responsible, is publicity, to create fear by manipulating the media.
It seems that Owen was aware that there was such a small window of opportunity for the offender to strike unseen and knows that base on other witnesses testimony, they were alive at 11.15, Dead at 11.25, and only Owen passes the scene in between at approx. 11.20. Is this cause to make up the whole story of seeing a second vehicle there? Absolutely. But that 'alibi', even though essential to invent it to divert suspicion and offer a whole second scenario of a killer there as Owen Passes, is not backed up by any of the other witnesses on Lake Herman who report seeing no passing vehicles around the time of the murders or in the immediate aftermath.
By the time of the second interview, Owen probably knows the timeline the police have put together and knows he's the only one that has the opportunity to have been there offender. So, as if out of necessity rather than choice (as he sees it) he decides to throw in the "Ohhh yes, by the way, about 45 secons, maybe a minute after I passed there, I heard what I though was a gun shot." And this had slipped his mind in the first interview where he knew that a double homicide had occurred with both being shot to death? In Z's own words I would reply to that with; "Bulls*it. If guilty of this crime and knowing the police had worked out a timeline that allows approx. 6 minutes for the offender to strike and escape and he's the only one that passes there in that six minute time frame, you'd expect a guilty man to come with something like this to try and avoid becoming 'suspect' and remain the helpful 'Witness' by saying "It wasn't me that did this, but I did hear the shots being fired by the man who did."
Several of Owen's comments also seem suspicious, or at the very least raise an eyebrow at. The Second interview Owen is said to state "There definitely were two cars there." The way that is stated, to me anyway, is as if he's replying to someone who questions his two cars in entrance claim, maybe the officers confronted him with the fact that no other witnesses saw a second vehicle there or remember passing one on Lake Herman itself. That would warrant Owen making such a remark as "There definitely were two vehicles there."

