Colonel Curry said it was standard to discipline detainees when they did not follow procedure.

Mr. Ani despaired of ever being released. His letter that was printed in The Times ended with, “I hope I can be dust in the storms of Bucca so that I can reach you.”

Dangers Beyond Jail

“I didn’t see any kind of solution for me,” Mr. Ani said after his release. “The only solution was to die,” he said, his eyes welling with tears. “I was hoping to die.”

In releasing Mr. Ani, the American military transferred him to Camp Cropper in Baghdad and gave him $25, which he and his parents used to hire a taxi. Along the way home, they had to dodge Shiite-controlled checkpoints, and just days later, he said, he narrowly escaped capture by a Shiite militia. Mr. Ani and other Iraqis say they believe these militias have found a way to learn when Sunni men are released from jail and then hunt and kill them.

Maj. Gen. John D. Gardner, commander of American detainee operations, said that he had heard such concerns and that he was trying to alter the process of releasing detainees to improve their safety.

Mr. Ani said that for him there was only one way to stay alive: flee Iraq.

He said he was scared and puzzled about his next step. He said he felt that he could not stay in Syria, if only because work was scarce. But he must compete with other refugees for the attention of another host country.

“Until now, I can’t sleep, really,” he said. “Whenever I hear something noisy I stand up. I’m in a very bad psychological situation. I can’t stop thinking of what we should do. I don’t have a future here. How should we live?”

When his uncle put on Al Zawra, the satellite television station, Mr. Ani turned to look at the scenes of Sunni children who had been killed and the attacks on American soldiers.