Michael Karkoc, the Nazi next door. Photo: Chris Polydoroff/The St. Paul Pioneer Press/AP

When 94-year-old Minnesotan Michael Karkoc was revealed to be a Nazi war criminal last Friday — thanks to the ill-advised tell-all memoir he published — his friends and neighbors were, understandably, shocked. An actual OG Nazi! In Minnesota! In the year 2013! It’s almost incomprehensible.

But Rabbi Marvin Hier, the founder of the Simon Wiesenthal Center — named after the world’s foremost Nazi hunter — was hardly surprised. When we asked him how many Nazi war criminals may be living in the United States, Hier told Daily Intelligencer, “It could be hundreds.”

“Normally I would have said thousands,” he added, “but they’re in their eighties and nineties, and many of them may have died. So it’s very hard to give you an exact figure of how many cases there are like the one in Minnesota in other parts of the United States. But it is fair to say that there could be many.”

Nazi war criminals are, obviously, not America’s ideal immigrants. So how did this happen, exactly?

In the forties and fifties, “immigration officials were not sufficiently briefed and knowledgeable about the [Nazi] auxiliary units,” Hier says. “They thought of the SS in terms of Germans or Austrians, but they didn’t know that wherever Hitler went, there were groups of citizens of those countries that assisted the SS in their tasks. That knowledge came much later on.” And when these local collaborators sought entry into the United States, “they had a common story, which was they were escaping communism.”

A 2008 report by the Justice Department’s Office of Special Investigations entitled “Striving for Accountability in the Aftermath of the Holocaust” states that “one of OSI’s early Directors hypothesized in 1984 that approximately 10,000 Nazi persecutors had emigrated to the United States.” However, the report added, “In retrospect, that estimate seems high.”

Of those Nazi collaborators who did make it into the United States, many are long dead. But a lot of them, presumably, aren’t.

“You have to take into account that at least many tens of thousands or even hundreds of thousands of men (and some women) were participants in these crimes at a relatively young age,” says Efraim Zuroff, the director of the Simon Wiesenthal Center’s Israel office and “the world’s last active Nazi hunter,” according to the Times of Israel. “And that thanks to the progress of modern medicine, many live today to age 90 and above.”

“I often say that people without a conscience live longer,” Zuroff quips. “Less stress.”

It’s still likely that the harmless-seeming nonagenarian next door who gives out dried apricots on Halloween and wears old-timey hats and spends twelve minutes grabbing the morning paper is not, in fact, a Nazi war criminal. But, at the same time … we’d watch out for those apricots.