Yeah, you don’t have to reinvent the wheel every time you want to do a genocide. Death marches work really well if you’re trying to hide your crimes because they spread the bodies out and it is normal for travelers to die along the roadway. That’s what you do if you’re in a hurry. If you’re patient you just starve them to death like in the Eisenhower camps, but then you need a reasonable explanation for all of the corpses.