This is the person I believe may have been the Zodiac Killer for reasons stated in the article:
He knew 3 of the victims, going to school with 2 women and working with a third victim.

The "Zodiac" sign was actually a Celtic cross ( I've always thought this was likely).

He was very young, and in a rage because his girlfriend left him. There were no killings while he was in the military.
He worked at an Army surplus store and likely wore boots like boot prints found at one crime scene.

He told 2 friends he was " a killer", in 1976 to a moron who didn't believe him, and when he had cancer in 2002. The second friend did believe him based upon the details of his confession. Friend promised not to tell anyone until after suspect died. He kept his word.

Both witnesses to the confessions are named. If this can be proven, I hope they serve time for obstruction of justice or some other charges. Parents and siblings have died when they could have possibly had some amount of closure. If they are lying, then I hope they are punished for lying to the media ( but I don't think they are lying).

This guy was no mathematician. He was very young, the age of his victims.

Motive given was that his girlfriend broke up with him in 1968 and he couldn't cope with his rage. They were all rage killings except for Paul Stine, who was killed " for drug money".