WASHINGTON (AP) — President Barack Obama on Thursday capped a swift and forceful response to an Associated Press investigation by signing into law a measure that bars suspected Nazi war criminals from receiving U.S. government pension benefits, known as Social Security.

AP’s investigation, which was the impetus for the No Social Security for Nazis Act, found that dozens of former Nazis collected millions of dollars in retirement benefits after being forced to leave the United States. Recipients ranged from the SS guards who patrolled the Third Reich’s network of camps where millions of Jews died to a rocket scientist who helped develop the V-2 rocket that Nazi Germany used to attack London.

The speed with which the legislation moved underscored the outrage AP’s findings triggered among lawmakers in Congress — and American taxpayers. The House unanimously approved the bill Dec. 2 and the Senate passed it by voice vote just two days later.

Mike King, a Vietnam veteran and a retired police office, gets a Social Security check of $900 a month. That’s less than half of what he could be getting based on his years in the workforce. But his benefits are reduced because of a rule that docks retirees who simultaneously collect a public pension. It’s “appalling,” he said, that former Nazis collected benefits when he and others in his position are forced to accept less.

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