When Adam fell, he took with him our entire unfortunate race. When Adam died, we all died with him. When Adam transgressed, transgressing became part of how I experience being human.
Adam did not intend to become a murderer. The real murderer was the serpent. All the same, it was through Adam that Satan carried out his murderous plans, and he made Adam an unwitting party to the genocide of his entire race.
In scripture as in modern law, murder need not be a hands-on business.