[thunderfork]

"one can say a group took an action in some cases, so it must be right to say a group took an action in this case" is not compelling.

[Manuel_D]

The point is they're both cases where a group of people get together to carry out a criminal act of violence. The fact that only one individual actually fired the gun or tied the noose doesn't alter the fact that the group as a whole carried out the criminal plan.