What proof Zodiac did Lake Berryessa?

It is true that the killer did call the police but I'm not sure if it was public knowledge at the time if the killer of the July 4th crime called the police or not. Someone can verify that.

I don't know if it was said the writing was the same on the car or not.

As for the voice and build, a lot of people can have that description. Average males in their late 30s tend to be overweight and many people have similar sounding voices.

I just think a gruesome attack at the lake, Zodiac would have bragged about it. But he never mentions it once.

I could be barking up the wrong tree here. But imagine all these years this wasn't even a zodiac crime.

Yes, that's well stated, sgtpowers. Why would a "copycat" don an elaborate costume, attack in broad daylight on a relatively open, grassy lake-shore, then switch from gun to knife to commit his crime if he were indeed a copycat? People may offer further speculations, but I believe those will not stand up to Occam's razor*, i.e., the least amount of assumptions points to the Zodiac as the Lake Berryessa responsible. He was intensifying/expanding his M.O. This is common behavior for serial killers.**

The fact that Bryan Hartnell survived and related the events to law enforcement and the media did work in Zodiac's favor. Why would Zodiac need to follow up with the newspapers?

Furthermore, people often overlook the fact that just two weeks following the Lake Berryessa attack, the Zodiac carried out the Paul Stine cabbie murder (Oct.11, 1969), involving planning, preparation, and the mailing of a letter of responsibility immediately after committing the crime. Four weeks after that, Zodiac devised, completed, and sent the 340 cipher (Nov.8, 1969). No matter what anyone believes the cipher may or may not say – look at it – that thing wasn't put together overnight! If the zodiac worked at least part-time (probable), then he obviously had a lot more on his plate during these months—his most active period—than to concern himself with seeking redundant credit for Lake Berryessa.

NOTE: Members of one or more of the amateur community Zodiac research sites have identified the significance of the "candy cane"-style lowercase "f", 3-stroke "k", and low-cross "t" found on the VW Karmann Ghia car door and in canonical (acknowledged) Zodiac communications. [Specific observations made by community member, Bently, a.k.a., Wrench.]

Other researchers have also pointed out the parallel of the "by knife" from the car door and the hand-printed "By KNiFE" on the back of the Halloween card, which Zodiac mailed Oct.27, 1970 (exactly 13 months later).

* "Among competing hypotheses, the one with the fewest assumptions should be selected."
https://simple.wikipedia.org/wiki/Occam%27s_razor

**The MO is what the offender must do in order to commit the crime. For example, the killer must have a means to control his victims at the crime scene such as tying them up. Significantly, the MO is a learned behavior that is subject to change.

A serial killer will alter and refine his MO to accommodate new circumstances or to incorporate new skills and information. For example, instead of using rope to tie up a victim, the offender may learn that it is easier and more effective to bring handcuffs to the crime scene.

— Scott A. Bonn Ph.D.

I'm not saying different people killed in every single attack. But I wouldn't be shocked if some tried to do their own attack to make it look like Zodiac we just don't hear about it. But maybe this one is the only one that people believe it was.

It's the only attack that was by knife
It was odd he wore a costume if he was gonna kill them anyways.
There is a sketch of a strange man (we see a glimpse of it at the end when Dave flips through the files) looks nothing like the popular SF sketch (which I hate they never showed in the movie)

I think the Lake Herman Road, Blue Rock Springs and Washington/Cherry killings were done by the same person and writer. I just wouldn't be shocked if Lake Berryessa attack was some copycat considering that it was the most gruesome attack yet Zodiac never makes a mention of it.

He says he killed 5 after the Paul Stine murder because he already acknowledged Mike Meagau survived. Maybe he was counting Cecelia and assumed Bryan died too.

That's what I read after. And I get the writing was done too fast to be manipulated. But I don't get how writing on a car can match the writing on a paper. A lot of people's writing on a chalk board is different then writing on paper in school.

I'm no conspiracy theorist. But I just find it weird Zodiac never bragged about his costume, the way he stabbed the girl or any reference or confirmation he did that crime. In the Vallejo crimes Zodiac said what the victims where wearing, where they were sitting and what kind of bullet and fun he used.

Thats why it's hard to believe its the same guy.