I read this a few years ago, but I don't recall a lot of detail, but the main takeaway was that the Mason characters were all actors, and that the murders were faked.
It's quite a long pdf and there is a lot of speculation, but it is an interesting read. This same researcher also wrote a compelling document suggesting that John Lenon is still alive living under the name Mark Staycer, which also has a few tie ins to the Manson murders.
The Tate Murders were a False Flag (pdf)
Of all the “conspiracy theories” I have run across over the years, amazingly this is not one of them. I searched the internet for anything on this theory and got nothing, even at Above Top Secret and sites like that. But now that we know many recent tragedies have been faked in Hollywood fashion, why not go back to previous decades, to see how long this has been going on?
Before I start, let me say two things. One, we will have to study the crime scene photographs of Sharon Tate, but I will make it as easy on you as possible. They aren't what you think anyway. I was apprehensive when I clicked on them for the first time, but I was very surprised. They aren't at all what we have been led to believe.
Even so, I will lead you in slowly, making a strong case that they are fake before you even take a look [If you want to skip ahead, go to p. 46]. By the time we get there, you will already be pretty sure they aren't what they are supposed to be, and you won't be afraid to look at them. Two, I will also prepare your mind and eyes by making it clear why the murders needed to be faked. It will be much easier for a reader to understand how they were faked once he or she understands why they were faked.