This is a line from a game that I'm attempting to take apart and understand. A man has committed a murder, and is panic-thinking he doesn't want to be caught for it. He thinks/says out loud this sentence:
誰か ... 誰かがやったことにするんだ ... ！
I'm guessing this is essentially, "Someone ... someone [else?] will have done this," as in, he's going to pin the crime on another person.
I'd like to make sure that I'm understanding 「やったこと」 and 「するんだ」 correctly. The first, breaking down やった and こと would probably be something like, "thing that was done." But the second is probably me not quite clicking with the ~んだ ending - is that him answering his own thoughts? Or is it a tense of some kind? I understand it's meant to be explanatory, but it's not until after this that he decides he'll accuse a man he saw, so I would have guessed the tense would appear there instead.
In case it has to do with him answering himself, for context, the lines before this one are:
... くそっ！なんでオレがこんな目に ....
... つかまりたくねえ ... こんなことで ....