Mubaraks' probe is also seen as a way to help amend weeks of souring relations between the protest movement the Egyptian military, which took control after Mubarak was toppled. The protesters say the investigations are slow, and are outweighed by rights abuses by the new rulers.
They have also criticized the army for being too close to the old regime and not swiftly bringing Mubarak to trial while hundreds of protesters remain in military detention following a demonstration last month and others received swift trials before military courts.
Wael Ghoneim, one of the activists who organized the uprising against Mubarak, which started Jan. 25, commented on Mubarak's detention with a tweet: "Justice in action once again."
While the ex-president was taken to the hospital in Sharm el-Sheikh, where he has been living since being removed from power, his sons were taken for questioning to the nearby courthouse by prosecutors from Cairo.
An angry crowd of 2,000 people had gathered outside the hospital late Tuesday, demanding the sons' arrest. Then, in the early hours Wednesday, head of provincial security in the South Sinai told the crowd that Gamal and Alaa would be detained.
"Brothers, whatever you wanted, you have got ... 15 days," said Maj. Gen. Mohammed el-Khatib, as the crowd erupted in cheers.
As a police van with drawn curtains took away the brothers, the crowd pelted it with water bottles, stones and their flip-flops, a sign of disrespect in the Arab world.
Later, an airport official at the Sharm el-Sheik airport said the sons have been transferred aboard a private jet to the Torah prison on the outskirts of Cairo. The official spoke on condition of anonymity because he was not authorized to speak to the media.
The increasing role of Gamal Mubarak in the government over the last decade and the belief that he might succeed his father helped galvanize Egypt's protest movement.