I understand Monsieur Ménard's point--if you don't mind, Monsieur Ménard.
To gather evidence that a carload of individuals popped off somebody who may have been unrelated and drove on, even though they may have been targeting someone they wanted to drop or shoot or kill, in order to prove that the group was attempting to shoot someone else because it would have been of benefit to them--maybe it was somebody in the same business, pushing drugs, and they want to knock him off--but they didn't kill him, they killed someone else, the police have to gather evidence to bring it all the way back and prove that this was the reason they did what they did.
Since it's a criminal organization that's dealing in drugs, the evidence would have to show clearly that the link is there. If they cannot show that, they can't charge that.