Very interesting story. Even though the ballistics test proved their guilt decades later the trial was a sham and they should have been acquitted. Amazing how a fascist even came to their defense.
So much of forensics is cargo-cult "science" that starts with a conclusion and works backwards to prove it. Furthermore, the analysis is frequently subjective and without a control.
Here is an article on ballistics testing in particular that highlights some criticisms.
But these were two guys fighting against the robber barons and the rise of capitalism as we know it today. Yeah, a couple other working class people died as a result, but it’s hard to see it as cut and dry as all that. How many people have died of capitalism. The body counts are way, way out of balance.
Here's the Wikipedia article on them. The film Sacco & Vanzetti was based on their case. Its title song Here's to you by Joan Baez and Ennio Morricone is probably known to some.