The Nigerian suspect, Umar Farouk Abdulmutallab, was moved to prison from a hospital. He was not expected to appear at a 2 p.m. EST court hearing on Monday in Detroit, where prosecutors plan to seek an order to obtain his DNA.

Abdulmutallab, 23, is charged with attempting to blow up a Northwest Airlines jumbo plane as it approached Detroit on a flight from Amsterdam with almost 300 people on board.

Asked whether al Qaeda was involved, Homeland Security Secretary Janet Napolitano said, "That is now the subject of investigation and it would be inappropriate for me to say and inappropriate to speculate.

The incident exposed still-raw nerves in the United States eight years after the September 11 hijacked plane attacks, as well as the political divisions that have emerged since. A sick passenger on the same Amsterdam-to-Detroit flight caused a major security scare at the Detroit airport on Sunday while Republicans began criticizing the Obama administration over anti-terrorism efforts.

A US law enforcement official, speaking on condition of anonymity, confirmed media reports that Abdulmutallab had told investigators al Qaeda operatives in Yemen had given him the device and told him how to detonate it.

On Friday, Abdulmutallab was overpowered by passengers and crew after setting alight an explosive device attached to his body, and was treated for burns at a Michigan hospital. He was released and transferred to a prison on Sunday morning.