When the CIA met prisoners at Guantanamo, they used torture.
When the FBI met prisoners at Guantanamo, they used... something else.
My strong belief: whether "torture works" depends on what you really want. If you want to break someone -- to force them to sign confessions, to make them say anything in front of a camera -- then torture works. If you want to know the truth, then don't use torture. You can use many tricks to quickly gain trust -- see "neuro-linguistic programming" in any bookstore.
Torture works only when the information provided can be immediately verified.
Example: (T)orturer (V)ictim
T What is the frequency?
V (lies)
T (tests frequency, fail)
T PAIN! . . . (repeat)
V OW! . . . (repeat)
V Stop already! The frequency is (true)
T (tests frequency, pass)
T Now we're talking. What is the next frequency?
V (thinks, "damn")
As opposed to most Gitmo interrogations:
(I)nterrogator (S)ubject
I Tell me where the safe house is!
S No!
I I can yell at you all night . . . (repeat)
S OK . . . (repeat)
I (After many days, breaks S's brain.)
S The safe house is in Morocco.
I (Checks, is told 'You don't have security clearance for that')
I You lied.
S You have no idea whether I tell the truth or not, do you?
S Lies . . .
I Tears hair out . . .
When you make this step you are already past the gates of Hell.
Torture is so non productive in every way. Any prisoner who tells anything is suspect, in my humble. Self preservation will always win.
The Spanish Inquisition used waterboarding and all it got them was a reputation.