Confined to the basement of a CIA secret prison in Romania about a decade ago, Khalid Sheikh Mohammed, the admitted mastermind of the 9/11 terrorist attacks, asked his jailers whether he could embark on an unusual project — Would the spy agency allow Mohammed, who had earned his bachelor’s in mechanical engineering, to design a vacuum cleaner?

The agency officer in charge of the prison called CIA headquarters and a manager approved the request, a former senior CIA official told The Associated Press.

So, using schematics from the Internet as his guide, Mohammed began re-engineering one of the most mundane of household appliances.

That the CIA may be in possession of the world’s most highly classified vacuum cleaner blueprints is but one peculiar, lasting byproduct of the controversial U.S. detention and interrogation programme. By the CIA’s own account, the programme’s methods were “designed to psychologically ‘dislocate’” people. But once interrogations stopped, the agency had to try to undo the psychological damage inflicted on the detainees. The CIA apparently succeeded in keeping Mohammed sane.

Others haven’t fared as well. Other accused who were locked up in Poland and Romania with Mohammed, have had mental issues. Mohammed was subjected to harsh interrogations in Poland. Agency officers and contractors forced him to stay awake for 180 hours, according to a CIA report. He also underwent 183 instances of waterboarding.

In Romania, the prison provided books for detainees to read. Mohammed, former officials said, enjoyed the Harry Potter series. In Graham Greene’s spy thriller Our Man in Havana, a vacuum salesman in Cuba agrees to work for MI6, the British spy service. He dupes the British into believing his vacuum designs are military installations. The AP was unable to determine whether Mohammed ever read the famous novel.