In the aftermath of 9/11 and the invasion of Afghanistan, American jailers at Guantanamo Bay subjected prisoners of war to a battery of interrogation techniques: waterboarding, stress positions, and – weirdest of all – the beloved children’s show Sesame Street.

Songwriter and musician Christopher Cerf, who's written for Sesame Street for decades, was outraged to learn that his compositions were used to break down Guantanamo detainees, not educate children. But it also prompted him to dig deeper into the use of music to torment prisoners. Al-Jazeera documents his investigation: