SAN’A, Yemen—Osama bin Laden’s former driver returned home to Yemen Wednesday to serve out his remaining prison sentence after the U.S. released him from Guantanamo Bay, American and Yemeni officials said.

Salim Hamdan was transferred to Yemeni custody and taken to a state security prison after he arrived at a military base at San’a International Airport Wednesday night, a Yemeni security official said.

Hamdan was the first man to go before a U.S. war crimes trial since the end of World War II. He was convicted on Aug. 6 of providing material support to terrorism, and the military said it could keep him locked up indefinitely if it considered him to be a continued threat. Instead, he was sent back home to Yemen early.

Hamdan’s U.S. military attorney said the 40-year-old father of two was incredulous when he learned Saturday he being sent home to Yemen.

“The defense team spoke to him on the telephone on Sunday morning. He was still in a state of disbelief,” Navy Lt. Cmdr. Brian Mizer said Wednesday.

Hamdan was sentenced at the trial to 5 1/2 years in prison. He was credited with five years and one month time served so his sentence ends on Dec. 27, the Pentagon has said.

Mizer said he did not know what set-up the Yemeni authorities have for keeping Hamdan detained until his release date.

The jury of military officers convicted him of supporting terrorism but acquitted him of being part of al-Qaida’s conspiracy to attack the United States. He was also cleared of providing missiles to al-Qaida and knowing his work would be used for terrorism.