The family of Mark Frerichs on Monday urged U.S. President Joe Biden to fire his chief Afghanistan peace negotiator, charging that the envoy has done little to win the release of the last American believed to be held hostage by the Taliban.

The 59-year-old U.S. Navy veteran from Lombard, Illinois, worked in Afghanistan for a decade on development projects. He was abducted the month before Khalilzad signed the U.S. troop pullout deal and was transferred to the Haqqani network, a brutal Taliban faction accused of some of the deadliest attacks of the war.

The network's leader, Sirajuddin Haqqani, who has a $10 million FBI bounty on his head, was named interior minister last week in the Taliban government announced after their lightning takeover of Afghanistan as the last American soldiers left.