User blog comment:Llama919/Possible Beast Titan Identity?/@comment-5774380-20150618200119/@comment-26509561-20150618225853

The way he said those words to mike seem to me like he is simply being an ass. The way he spoke when he took the gear really shows us his sadistic attitude. And that he knew exactly what it was. And what he said after abandoning him to be eaten was pretty messed up manner.

I wouldn't expect the father of Erwin to be as horrid as such but surely life outside the walls could change a man drastically, and if it is Erwin's father, we would likely have to wait until the end of the story arc to find out unfortunately. So I furthermore don't have too much more to say about this theory, but I will expand upon this post and the information provided in the comment section is helping this develop, so again I appreciate the feedback.