Did the Enginner kill his mates?

I read some people talking about the Engineers Hypersleep pods having holes in them, except for the sleeping Engineer [aka Bob]. So I ask you about the possibility that Bob actually killed the rest of the Engineers via something that he left loose at the Temple/Juggernaut. That would prety much answer the fact that the other Engineers were piled and that he was the only one alive. The dude killed them and piled them like garbage bags. Perhaps he went into Sleep while waiting for that "something" to die of it's own. As an extra I'll even dare to say that the idea of going to Earth with not so good intentions was Bob's. Maybe he was a sort of insane Android like Mofo. And perhaps that would explain why he snaped David 8's head [maybe because he recognise him as an Android?] Or better yet, he was just plain nuts. Anyway, the idea is this: -Bob kills his mates and piles them - Bob doesn't care at all for them and leave them ... piled... and headless. Thoughts? Anyone?