What makes you think that they somehow cannot apprehend a serial killer with a bunch of codes unless it's a government stooge? US was already in the process of being a surveillance empire during that point and for all we know Mengele went to the US to assist the CIA in committing more illegal mind control experiments.
What makes you think that they somehow cannot apprehend a serial killer with a bunch of codes unless it's a government stooge? US was already in the process of being a surveillance empire during that point and for all we know Mengele went to the US to assist the CIA in committing more illegal mind control experiments.