The hobbies of Khalid Sheikh Mohammed, the mastermind behind the 9/11 terrorist attacks, while in a secret CIA prison in Romania apparently included reading and designing a vacuum cleaner. KSM enjoyed reading the “Harry Potter” series and CIA officials complied with his requests in order to keep the prisoner from going insane.

A new report by the Associated Press details Mohammed’s stay in one of the secret CIA prisons used to hold suspected terrorists. According to the CIA official, speaking to AP anonymously, the agency believed Mohammed could providence evidence against other terrorists and would need to be declared sane if he was to face a trial in the future. In order to make sure he stayed sane while being detained in a prison and after he was subjected to interrogations meant to physically, and mentally, isolate individuals from society, the CIA agreed to several of his requests.

Perhaps the most unusual is Mohammed’s request to design a vacuum. Mohammed, believed to have been born in Baluchistan, Pakistan, or Kuwait, graduated from the North Carolina Agricultural and Technical State University with a bachelor of science in mechanical engineering. Soon after his capture, and interrogation in Poland, Mohammed was transferred to the secret prison in Bucharest, named “Britelite,” reports AP.

While in prison, Mohammed used designs found on the Internet to guide his vacuum development and also spent hours with CIA officials discussing his biography and his terrorist activities. The vacuum cleaner designed by Mohammed is classified as an operational file and will never be publicly released. Mohammed also had “homework” that would detail his knowledge about al-Qaeda and its activities, notes AP. As a reward for his efforts, he would be given Snickers candy bars.

In addition to building a vacuum, KSM spent time reading and enjoyed the “Harry Potter” series, the report says. CIA officials had to be careful of any activity and would examine every book Mohammed read for coded messages to other prisoners, reports AP. In one instance, he was caught trying to pass a message to not share information about Osama bin Laden’s courier to other inmates.

Another interesting about the vacuum is that it fits in with a novel’s plot about a spy trying to pass off designs of a vacuum cleaner as sensitive military material, reports AP. Graham Greene’s “Our Man In Havana” is a black comedy about a James Wormold, a vacuum cleaner salesman, who is approached to work for the British spy agency MI6. Wormold fakes his reports to MI6 and even includes designs of a vacuum cleaner as evidence of a military installation. The AP couldn’t confirm with their source if Mohammed had access to Greene’s novel.

Mohammed confessed to orchestrating the 9/11 terrorist attacks after CIA torture that included sleep deprivation of 180 hours and 183 waterboarding sessions. He is currently being held in the Guantanamo Bay Detention Center.