That means a war between Detective Bureau and the killers of that dead detective.
We need to take revenge to the dead detective. It was one of ours.
That means a war between the Detective Bureau and the killer(s) of that detective.
we found the dead detective and we know where the killer is, so we track him and breach him
That means war between Detective Bureau and the killers of that dead detective
We need to revenge him, the dead detective was a part of us.