“He pulled the trigger before he cocked the gun. When he cocked the hammer he thought it would be held by the sear. Let go of the hammer and the gun fires”
Yeah, he’s guilty. He held the weapon, aimed and fired and killed the woman. His responsibility. But who and why loaded the weapon on a movie set??
” But who and why loaded the weapon on a movie set??”
For whatever reasons, the crew apparently used the “prop” gun for fun using live ammo. Who knew about that and didn’t ban it?
Your final question is why more than just Alex is guilty here.
Finally someone explains it
The general public doesn't understand how a movie set works, especially when firearms are being used. The armorer and his/her team are completely in control of all weapons. An actor should never check a gun, chamber a round, etc., UNLESS it's called for in the script. If an actor mishandles a firearm in any way, the Director or armorer can call cut and the armorer would then collect the firearm, recheck it, and then hand it back so the scene can be filmed again.
The really big question, in this case, is how did a live round get not only on the set, but in the gun? That's a HUGE no no. Hollywood movies feature firearms all the time, and there's a reason why accidents are so very rare.
Baldwin may be held responsible for squeezing the trigger, especially if the scene didn't call for him to do so. Another big worry he has is his role as Executive Producer. He had skin (money) in this movie. If he cut any corners, and it can be proven, he'll be in real trouble.