A German-born Turkish citizen held for more than four years at the U.S. terrorism detention center at the American naval base in Guantanamo Bay, Cuba has been released and returned to Germany.

Attorney Bernhard Docke said his client, Murat Kurnaz, was flown to a U.S. Air Force base in Germany and released Thursday.

Kurnaz was released after long negotiations between U.S. and German officials.

Docke said his client will undergo a medical examination and will refuse interviews as he adjusts to his newfound freedom.

Kurnaz was arrested in Pakistan in 2001 and transferred to Guantanamo Bay, where he remained for more than four years.

Docke said his client suffered abuse in the U.S. military prison, including sexual humiliation.