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.
Mengele actually went to the USA and is called the Zodiac Killer. The one that went to Argentina is Hitler.
The Zodiac Killer?
Not saying it's Impossible, but are there any correlations besides the codes?
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.