A U.S. civilian contractor believed to have been kidnapped in Iraq in January was returned to American authorities last week, the Department of Defense said.

Issa Salomi, 60, of El Cajon, California, became unaccounted for on January 23 and was believed to have been kidnapped in Baghdad, the Defense Department said Saturday.

Salomi worked as a civilian linguist for United States Forces – Iraq since May 2009.

The circumstances of his ordeal remain under investigation, the department said.

"This is a traumatic time for the Salomi family," read a family statement released by the FBI office in San Diego, California last month. "We appreciate all the support everyone has shown towards us from all over the country, and we all share their heartfelt compassion."

"We are confident that everything is being done by the most capable people here and abroad to bring Issa home safely, and we all are anxiously awaiting his safe return," the family had said. - CNN's Mohammed Tawfeeq contributed to this report.