Mohammed graduated from North Carolina A&T State University with a degree in mechanical engineering in 1986. It’s not clear whether Mohammed was interested in designing a better vacuum or had ulterior motives. He might have intended to use the plans to conceal secret information or trick his jailers.

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.

It remains a mystery how far Mohammed got with his designs or whether the plans still exist. The secret CIA prison in Romania was shuttered in early 2006 and Mohammed was transferred later that year to Guantanamo Bay Naval Base prison, where he remains. It’s unlikely he was able to take his appliance plans to Cuba.

Mohammed’s military lawyer, Jason Wright, said he was prohibited from discussing his client’s interest in vacuums.

“It sounds ridiculous, but answering this question, or confirming or denying the very existence of a vacuum cleaner design, a Swiffer design, or even a design for a better hand towel would apparently expose the U.S. government and its citizens to exceptionally grave danger,” Wright said.

But Wright added that he often discussed “modern technological innovations” and the “scientific wonders” of the Quran with Mohammed. He called Mohammed “exceptionally intelligent.”

“If he had access to educational programs in Guantanamo Bay, such as distance learning programs, I am confident that in addition to furthering his Islamic studies, he could obtain a Ph.D. in mechanical engineering, and very likely patent inventions,” Wright said.

The CIA won’t discuss the Mohammed’s vacuum plans, either. The AP asked the CIA for copies of the vacuum designs or any government records about them under the Freedom of Information Act.

The CIA responded in a letter to the AP that the records, “should they exist,” would be considered operational files of the CIA — among its most highly classified category of government files — and therefore exempt from ever being released to the public.