Justice Kagan's Response to Justice Roberts Leak Investigation

The Chief Justice had someone inside the court investigate instead of as you mentioned outside agency like the FBI so he could control it. I wonder if he really wanted to find out who leaked the draft opinion or if in fact he did find out and just hasn't told us. He's not prepared to deal with the blowback that he would get from exposing such a justice if he knows who it was. Some of the justices seem to be having a sort of debate in public by responding to what others have said in their public appearances.