So Joseph wanted Bart because he was the only white person right?

I mean there was the Asian guy, as he so called *beep* the "little turk girl" the "coon" and the dog. Eva was already part of the plan, so the only white person left was Bart, who he took a liking to make his doll. They do say that serial killers only kill from within their race right, or was he just racist?

Or was there a special reason why he chose him, I still don't understand that. I'm sorry if I sound like a moron.