I finished the game on casual and hard but was never able to set Willie free.
I read that’s it’s possible to free him once you are done with the factory.
But I am in the last part and have been robbed of most items.
Is it still doable at this point?
Yes.
Oh really?
“Yes.”
Wow!
Hmmm… Now you are making me doubt my (admittedly frail) memory. I’ll have to double check tonight, but I’m pretty sure I did it.
As long as you have the control over a certain person, you are able to free Willie.
Really, I didn’t succeed in freeing Willie. Could you give me a soft hint?
I did above.
I think it only works when the final guitar music plays.
@ZakPhoenixMcKracken: What have you tried already?
@milanfahrnholz: At the end you are able to end the stories of each of the main characters (except Delores). In this phase you are able to free Willie (or at least I was 
).
Yes, that´s what I meant with the part where the guitar music plays. I did that too after my attention was drawn to the possibility. My “wow” wasn´t really serious.
@someone: I tried to open the jail, but not in the last part of the game. So… only Delores can actually go to the jail and open it before entering the wireframe world?
@ZakPhoenixMcKracken I´m not sure who can or cannot do it. But I did it with Reyes, because he was the one who wanted to do it. Just open the jail cell before you hand over the evidence to Natalie.
You can only do it with Reyes since he’s the one feeling guilty about it.
Okay, that makes sense. Never occured to me to try with anyone else, anyway.
@ZakPhoenixMcKracken: The other gave the answers, nothing to add.
Just to be absolutely clear, I always assumed it was only with Reyes because he had a few dialogue options where he kept insisting that he knew Willy wasn’t guilty, and he felt bad about it. So that plot point was made clear by the story in the game.
ok, thank you to everyone. I had tried with Delores but never with Reyes. I just tried a few minutes ago, this time with the junior agent. Nice!
God I need glasses.