Valkavickas allegedly served in the Saugamus, Lithuania's secret police, between 1941 and 1944.

Valkavickas "played an essential role in a Nazi-ordered massacre of thousands of innocent civilians," said Eli Rosenbaum, the director of the Justice Department's Office of Special Investigations, which filed the motion on Monday of last week in U.S. Immigration Court in Chicago.

During the Nazi occupation of Lithuania from 1941 to 1944, approximately 94 percent of Lithuania's prewar Jewish community of 240,000 died in the Holocaust. Historians say the scale of the tragedy could have been smaller had ordinary Lithuanians not helped with the killings.

Valkavickas entered the United States in 1950 and applied for citizenship in 1994.

Sixty Holocaust perpetrators have been stripped of their U.S. citizenship since OSI began its operations in 1979, and 48 individuals have been removed form the United States.