I believe it was Sherlock himself who killed Michael. He hurt the person he cares for more than anyone else. Holmes is both angry and guilty about it. In the hospital scene, Joan says "just get him" and he nods. Later Sherlock is seen scrubbing the blood off the stairs. He wouldn't be doing anything other than looking for Michael 24-7 unless there was no reason to look for him. He just pretended to be shocked when the captain called with the news of finding Michael's body. In next week's preview, Sherlock asks Watson if she killed Michael. Not in a million years would he think that. He did that to throw her off base so she wouldn't suspect him. He doesn't want her to know, so she's not conflicted about his actions. Now why the FBI suspects Joan is a mystery. When he killed Michael, did he leave something behind that could be traced to her? Did he do it on purpose knowing that she has an airtight alibi and knowing he would always be willing to confess to prevent her from taking the fall? Or does the FBI agent secretly have it out for her and planted evidence? I am looking forward to finding out.
