Earlier quoted context omitted.
Here is the first paragraph of Manson's Wikipedia page: >Charles Milles Manson (né Maddox; November 12, 1934 – November 19, 2017) was an American criminal and musician who led the Manson Family, a cult based in California, in the late 1960s. Some of the members committed a series of nine murders at four locations in July and August 1969. In 1971, Manson was convicted of first-degree murder and conspiracy to commit mu…
The jury apparently believed otherwise. Besides, the history of the legal system is rife with instances of juries going along with prosecutorial bullshit.
That isn't how that works. The jury can't charge someone with a crime beyond what the prosecution argued.