Current and former U.S. officials interviewed for this article spoke on condition of anonymity because of the secrecy that still surrounds Holder's deliberations and the details of the interrogation files.
President Barack Obama repeatedly has expressed reluctance to launch a criminal investigation of the interrogation program, but has left room for prosecution of individuals who may have broken the law.
Obama and Holder have said they believe waterboarding constituted torture. An investigation would pose thorny political problems for the administration, and probably draw criticism over questions of fairness.
"An investigation that focuses only on low-ranking operators would be, I think, worse than doing nothing at all," said Tom Malinowski, advocacy director for Human Rights Watch. A probe also probably would drive a new wedge between the CIA and the Justice Department, agencies with a fractious history that have struggled to work more closely together since the Sept. 11 attacks.
Holder's interest in appointing a prosecutor to mount an investigation reportedly surged after he recently read a still-classified 2004 report by the CIA's inspector general citing extensive problems and abuses in the agency's interrogation program. The bulk of the report is expected to be released later this month.
Former CIA officials said the most disturbing section deals with waterboarding, a technique in which prisoners are made to feel they are drowning.
The Justice Department authorized waterboarding in an August 2002 memo that contained a caveat that could prove critical to any criminal probe. While allowing the approved methods to be "used more than once," the memo stipulated that "repetition will not be substantial because the techniques generally lose their effectiveness after several repetitions."
One passage of the CIA report declassified earlier this year said the method had been used "at least 83 times during August 2002" on Abu Zubaydah, the first senior al-Qaida figure captured by the agency. The waterboard was then employed "183 times during March 2002" on Khalid Sheikh Mohammed, the alleged mastermind of the Sept. 11 attacks. The inspector general also voiced alarm over how much water was being used. Rather than dripping liquid from a canteen, as the 2002 memo envisioned, CIA interrogators "applied large volumes of water," raising questions about whether the method "was either efficacious or medically safe."
