SAN JUAN, Puerto Rico -- An Afghan man who is being held as a former CIA terror suspect at Guantánamo has apparently gained extensive knowledge of western pop culture in an unlikely place: the detention center’s top secret prison-within-a-prison.

Nearly five years ago, Mohammed Rahim al-Afghani became the last prisoner sent to Guantánamo. He was accused of helping Osama bin Laden elude capture, and the CIA had interrogated him for months at an undisclosed location before he was locked away in Guantánamo’s Camp 7 — a prison unit shrouded in secrecy that holds about 15 men the U.S. government calls “high value” detainees because of their previous CIA detention.

With no court appearances, or even charges filed, nothing was heard from Rahim and he has remained largely a mystery. So, it was a surprise when his lawyer, Carlos Warner, released letters from the detainee described by the head of the CIA as a “tough, seasoned jihadist.” More surprising still was the content: quirky notes peppered with references to Howard Stern, Fox News and the global video hit of South Korean singer PSY.

“Dear Mr. Warner,” he wrote. “I like this new song Gangnam Style. I want to do the dance for you but cannot because of my shackles.”

In another letter, the multilingual Rahim shows some familiarity with American slang. He tells his lawyer, most likely in jest, that he has adopted a banana rat, a rodent commonly spotted around the U.S. base in Cuba. “Tell the guards to leave my friend alone. They need to chillax.”

It’s hardly what one would expect from a middle-age Afghan who has never been to the U.S. While there is still little public information about Rahim, the letters provide some insight into the man – and suggest that the prisoners in Camp 7, a group that includes five charged with aiding and orchestrating the Sept. 11 terror attack, are not completely isolated from the outside world.

To Warner, a federal public defender for the Northern District of Ohio, the letters humanize a man who he contends has been demonized by U.S. authorities, who allege he worked as a translator and assistant to bin Laden and other al-Qaida leaders. The lawyer says the letters demonstrate a surprising amount of resilience.

“It shows he’s different and he’s intelligent,” Warner said. “Just think that he’s doing this under all the restrictions that’s he’s under down there. He has an incredibly good sense of humor.”

There have been letters released to the media in the past from other detainees at Guantánamo, often providing valuable information about a prison that will have been open for 11 years on Jan. 11. Sami al-Haj, an Al-Jazeera journalist when he was captured and sent to Guantánamo, provided detailed accounts of a hunger strike before he was eventually released. Shaker Aamer, the last resident of Britain still held at the prison, has given an insider’s view on confinement conditions.

Rahim’s are different because he is in Camp 7, and the content departs so sharply from what one might expect from a jihadist. “I want you to contact Amanda Palmer,” he wrote Nov. 6, referring to the American singer. “… Ask her to write a song about me and my family.”

Warner and U.S. officials are prohibited from publicly discussing Rahim’s life and the allegations against him, but the broad outlines are in a public document filed in federal court by the government in response to Warner’s filing of a civil writ of habeas corpus seeking the prisoner’s release.