David Fincher, thanks. 

I don’t think this case will ever be solved (Gary was never confirmed to be Zodiac, the FBI doesn’t agree that it was him). Evidence got lost, many practices of forensic science are not definitive, and there were problems with communication among the different jurisdictions.

Fincher does an excellent job highlighting how all these factors lead to the harsh reality that no answer will ever be proven. 

Knowing that the truth will never be confirmed is beyond frustrating and I’m grateful I’m not a character in Fincher’s work because I’d fall down the rabbit hole of trying to be an amateur detective and end up in someone’s basement.