You are only able to specifically control the actions of the named target, but their death can involve another person.
Ie you can say “so and so gets hit by a bus” and a random bus nearby will hit them, but you cannot say “so and so is killed by such and such” and have the second person kill the first. I believe both people die of a heart attack if you try.
One might assume they aren’t, since they asked someone to clarify. How nice of you to laugh at them instead of answering the question.