The way she said it, it was that the person watching it couldn't tell whether it was the broken neck or the head trauma that killed him, so... I think it's not unreasonable to think that they happened at the same time, don't you? Maybe from the fall?

Which... could mean he was still alive before being pushed off the roof. In fact... it would have to be, wouldn't it? We haven't found anything like a baseball bat that could have been used to hit him, so...