WASHINGTON — Just six days after the Sept. 11, 2001, attacks, President Bush signed a secret order that gave the Central Intelligence Agency the power to capture and imprison terrorists with Al Qaeda. But the order said nothing about where they should be held or how the agency should go about the business of questioning them.

For the next few weeks, as the rubble at ground zero smoldered and the United States launched a military operation in Afghanistan, C.I.A. officials scrambled to fill in the blanks left by the president’s order. Initially, agency officials considered a path very different from the one they ultimately followed, according to the newly released Senate Intelligence Committee report on the C.I.A.’s harsh interrogation program.

They envisioned a system in which detainees would be offered the same rights and protections as inmates held in federal or American military prisons. Conditions at these new overseas prisons would be comparable to those at maximum-security facilities in the United States. Interrogations were to be conducted in accordance with the United States Army Field Manual, which prohibits coerced, painful questioning. Everything at the prisons would “be tailored to meet the requirements of U.S. law and the federal rules of criminal procedure,” C.I.A. lawyers wrote in November 2001.