Hamburg, Germany ? A court acquitted a Moroccan on Thursday of helping the Sept. 11 hijackers while they lived and studied in Hamburg, citing a lack of evidence he was involved in the al-Qaida cell’s plans to attack the United States.

Abdelghani Mzoudi, a longtime acquaintance of lead hijacker Mohamed Atta who even signed his will, smiled silently as he left the state court a free man after only the second trial anywhere of a Sept. 11 suspect.

The verdict infuriated victims’ relatives and prompted Germany’s chief federal prosecutor to criticize Washington for refusing to allow testimony from a U.S. captive — Ramzi Binalshibh, believed to have been the hijackers’ main contact with al-Qaida. Even the presiding judge warned Mzoudi that his acquittal was “no reason for joy.”

“You were acquitted not because the court is convinced of your innocence, but because the evidence was not enough to convict you,” Judge Klaus Ruehle said in explaining the verdict. “In this case we have to give the defendant the benefit of the doubt.”

The U.S. Justice Department issued a statement saying it regretted the acquittal and defending its level of cooperation.

“The United States has cooperated to the greatest extent possible in this and other terrorism prosecutions in Germany, consistent with security interests critical to the United States and the international community as a whole,” spokesman Mark Corallo said. “Our cooperation with Germany will continue.”

The U.S. trial of alleged Sept. 11 conspirator Zacarias Moussaoui also has been denied access to Binalshibh and other al-Qaida prisoners. Prosecutors there have argued that national security would be gravely harmed if details were revealed about the captives’ sensitive interrogations.

Germany’s top security official, Interior Minister Otto Schily, expressed support for the U.S. decision to withhold the documents even as he called the ruling “disappointing.”

Mzoudi faced more than 3,000 counts of accessory to murder and charges of belonging to a terrorist organization allegedly led by Atta.