Long-time lurker/First-time poster here.
I know that there is another thread that sort of debunked this rumor when people found the bust for sale online, but I am beginning to think there might be a chance that it is legit. Please bear with me on this; it's not very often that I post in threads like this one.
Here we go...
Note the elongated skull that appears to be lighter or shinier on the top.
Here's the infamous mutating guy. At first I thought the idea of a crew member transforming into some sort of creature was ridiculous, but when I started to think about what an earlier poster said about the shedding of outer layer (or something of that nature) and noticed the enlarged cranium, face that has grown larger, and pattern on the forehead.
If you look the left (the front) of the creature's head, you can just about make out the shape of some sort of face. It's dark but it is there.
I know this one is a long shot, but if you look closely you can barely make out what appears to be a skeletal face. The top of the head looks torn, so it might not be a broken helmet like many have speculated. Maybe the top of the head was blown off with a gun and the creature is making a hasty escape while being engulfed in flames from flamethrowers.