Dozens of suspected Nazi war criminals and SS guards collected millions of dollars in U.S. Social Security benefits after being forced out of the United States, an Associated Press investigation has found.

The payments, underwritten by American taxpayers, flowed through a legal loophole that gave the U.S. Justice Department leverage to persuade Nazi suspects to leave the U.S. If they agreed to go, or simply fled before deportation, they could keep their Social Security, according to interviews and internal U.S. government records.

Among those receiving benefits were armed SS troops who guarded the network of Nazi camps where millions of Jews perished; a rocket scientist who used slave laborers to advance his research in the Third Reich; and a Nazi collaborator who engineered the arrest and execution of thousands of Jews in Poland.

There are at least four living beneficiaries. They include Martin Hartmann, a former SS guard at the Sachsenhausen camp in Germany, and Jakob Denzinger, who patrolled the grounds at the Auschwitz camp complex in Poland.

Hartmann moved to Berlin in 2007 from Arizona just before being stripped of his U.S. citizenship. Denzinger fled to Germany from Ohio in 1989 after learning denaturalization proceedings against him were underway. He soon resettled in Croatia and now lives in a spacious apartment on the right bank of the Drava River in Osijek. Denzinger would not discuss his situation when questioned by an AP reporter; Denzinger’s son, who lives in the U.S., confirmed his father receives Social Security payments and said he deserved them.

The Social Security Administration has refused AP’s request to provide the total number of Nazi suspects who received benefits and the dollar amounts of those payments.

AP last week appealed the agency’s denial of the information through the Freedom of Information Act.