Relatives say the 18-year-old son of a former police colonel who joined the extremist group Islamic State (IS) has been arrested.
Behruz Gulmorodov's relatives told RFE/RL on April 17 that he was detained three weeks ago and is being held incommunicado.
They said they have received no explanation of the arrest, which could not be independently verified.
Behruz Gulmorodov's father, Colonel Gulmurod Halimov, was commander of the Tajik Interior Ministry's special forces, known as OMON.
He went missing in April 2015 and later appeared on the Internet, saying he had joined IS.
Last August, the U.S. State Department called Halimov a key member of IS and offered a $3 million reward for information on his whereabouts.
Western media reports quoted Iraqi officials on April 14 as saying that Halimov was killed in an air strike in Mosul.