"That man over there, he speaks Spanish," said a soldier, pointing to a nearby Afghan.

Taj Mohammed spent four years as a detainee in the Guantanamo Bay prison for suspected terrorist. The goat herder convinced interrogators that he was innocent, was released in 2006 and he now works for Americans in Afghanistan. (ABC News)

That man, Taj Mohammed, wore a traditional thick, dark beard, but he also wore a fairly hip pair of dark sunglasses and smiled broadly while speaking a mix of English and Spanish.

"Guess where he learned to speak it?" the soldier asked, not waiting for an answer. "Guantanamo."

For Americans haunted by reports of Gitmo detainees being released only to resume their terror tactics, Mohammed offers the rare opposite of a one-time detainee who instead of hiding from the Americans or openly despising them, now works for them.

Mohammed, a sheep herder from Kunar Province, was imprisoned for nearly four years at Gitmo. He said he doesn't harbor hard feelings about his four years of captivity, suggesting it was his destiny. He used the time praying and learning about the Koran. He also worked on his English and learned Spanish, he says, from members of the Puerto Rican National Guard assigned to Gitmo.

He now speaks English, Spanish, Arabic, Farsi, Urdu and Pashto. He also has a great appreciation for pizza, brought to him by his legal team along with vegetarian subs, ice cream and nuts to make their meetings feel "less like a prison environment," according to his court-appointed lawyer Paul Rashkind.

Mohammed, who estimates his age in the early 30s, insists he was an innocent who was set up as a Taliban by an angry relative. Shortly after Sept. 11, Mohammed and his cousin argued. As punishment for Mohammad's beating his cousin with a piece of wood, Mohammed claims the cousin told American soldiers that Mohammed was Taliban. Mohammed was soon on his way to Guantanamo.

"He never did anything to deserve the detention to which he was subjected," his lawyer Rashkind to ABC News in an email. "When I was appointed to represent him, after years of his detention, we demonstrated to the government that he was simply a goat herder. Shortly after, he was released without explanation."

Mohammed was flown to Bagram Air Field in 2006 from where he took a taxi to his family's home near the Pakistan border.