Also, in that same scene with Mulder and Scully investigating LaBonge, towards the end of his demonstration (11:35-11:45) you can see his left sleeve go from pulled down to up and then back down. See more
So basically he died of a heart attack, somebody crept up behind him and sawed his head off, and then glued it back on all in the space of 30 seconds. Does that make sense to you?
No. What makes it even stranger still because as far as I can tell, this body has been dead for over a month. I see signs of refrigeration.
And yet he performed yesterday. What a trooper.