After September 11, 2001, the Central Intelligence Agency, with the approval of President George W. Bush, began a highly classified program of renditions and torture. While torture violates both US and international law, President Obama declined to hold any one accountable for the program, saying he was looking forwards, not backwards.
That policy, however, did not apply to whistleblowers. The Obama Administration prosecuted former CIA analyst and case officer John Kiriakou for revealing information about the US torture program. Kiriakou first confirmed the CIA had used waterboarding while Bush was still in office. In spite of the CIA filing a crimes report, they declined prosecution. But the Obama Administration, at the request of CIA Director John Brennan, revived the case and sent Kiriakou to prison.
To date, he remains the only person to be held accountable in connection to the torture program.