Lost : MIB body-snatching question

In S1, Jack finds his father's coffin but when he opens it there is no body. In S6 we learn that MIB was appearing to Jack as Christian. So from this I would come to the conclusion that MIB can possess the bodies of dead people. But then in S6 it shows MIB as Locke and real dead Locke in the same shot. If MIB was impersonating Locke, shouldn't Locke's body have been missing just like Christian's body was in S1?

Good question, I was thinking the same thing the other day. I think they messed up. Somebody please correct me if I am wrong.

No, the MiB just takes the form of dead people. He doesn't take over their bodies. Like with Alex and Yemi. This isn't confirmed in the show or anything, but most likely the MiB took Christian's body from the coffin, hid it to make Jack think that it was really his Dad. Hence Christian's tennis shoe hanging in the bamboo forest, it was snagged off his foot while being taken some place by the smoke monster.

I had never thought of that but it does make sense