The Nigerian accused of the Christmas Day airline bomb attack has been co-operating with investigators and providing fresh intelligence in multiple terrorism investigations, senior US sources said.
Umar Farouk Abdulmutallab's help could prove to be a national security victory and a political vindication for President Barack Obama, who has been under fire from politicians who say the administration botched the case by giving Abdulmutallab the right to remain silent rather than interrogating him as a military prisoner.
In the days following the failed bombing in Detroit, Michigan, in which former London student Abdulmutallab was said to have tried to detonate a bomb hidden in his underwear, a pair of FBI agents flew to Nigeria and persuaded his family to help them.
When the agents returned to the US, Abdulmutallab's family came, too, according to a senior administration official briefed on the case.
FBI officials continued to question him, working in collaboration with CIA and other intelligence authorities, the official said. Mr Obama has received regular updates on the interrogation.
A law enforcement official said Abdulmutallab had provided information about his contacts in Yemen, where an al-Qaida branch has claimed responsibility for the failed attack.
Before the attack, the US regarded the Yemen-based al-Qaida in the Arabian Peninsula largely as a threat to Yemen's stability, not within US borders.
Depending on how much he knows, Abdulmutallab's co-operation could help authorities better understand the organisation.
While the interrogation continued, White House and intelligence officials quietly seethed as political rivals accused them of putting lives at risk.
That criticism peaked last weekend when Senator Susan Collins of Maine, in the weekly Republican address, accused the administration of having "a blind spot when it comes to the war on terrorism".
Ms Collins said the administration "undoubtedly prevented the collection of valuable intelligence about future terrorist threats to our country".
Authorities had hoped to keep Abdulmutallab's co-operation secret while they continued to investigate his leads, but details began to trickle out during testimony on Capitol Hill last night, where FBI director Robert Mueller and director of national intelligence Dennis Blair confirmed authorities continued to get intelligence in Abdulmutallab's case.
"It is also my understanding that Mr Abdulmutallab has provided valuable information. Is that correct?" Senate Intelligence Committee chairman Dianne Feinstein asked.
"Yes," Mr Mueller replied.
Mr Mueller then confirmed that the interrogation had continued despite the fact that the suspect had been advised of his right to have a lawyer and remain silent.
Since the terrorist attacks of September 11, 2001, politicians and the courts have wrangled with the thorny question of how to treat suspected terrorists.
The US Supreme Court has not ruled on whether the government has the right to hold a civilian as a military prisoner and both times it appeared the court would get the chance to decide, President George Bush opted instead to bring the cases in civilian criminal courts.
Also unsettled is which system is better for gathering intelligence. The Bush administration, which authorised secret CIA prisons for interrogations, also repeatedly used the US court system to prosecute terrorists.
Some detainees at the US detention camp at Guantanamo Bay, Cuba, have provided valuable intelligence, while others have refused to co-operate.
Some suspects in the criminal system refuse to talk once they have a lawyer. Others, like Abdulmutallab, can be persuaded to keep talking.