Logistically speaking, it makes no sense to tattoo people you've slated for termination, let alone move millions of a mostly urban ethnic minority out of the cities to do so. The infrastructure to kill millions of people was already present in every western nation in the form of animal slaughter houses at the time. Also, collecting finger prints would be more than sufficient for identifying purposes. However, it needs to be understood that I've never seen the holocaust as being a Jewish exclusive historical event. Until fairly recently, I had always understood the holocaust to be in reference to the entirity of what is understood to be the second world war.