An elderly U.S. citizen whose son has been jailed in Iran for the past four months has reportedly been arrested by Iranian authorities.

According to a Facebook statement from the family, 80-year-old Baquer Namazi was taken into custody on Monday.

His wife believes he has been taken to the infamous Evin prison, where their son — Siamak Namazi — has been in custody since October.

Both the father and son are said to be dual U.S.-Iranian citizens.