"The face of Satan was here in Fallujah, and I'm absolutely convinced that that was true," said Lt. Col. Gareth Brandl, with the U.S. Marines.
The rooms were found by Marines following trails of dried blood, or the smell of death. Some rooms were hidden behind fake walls, or concealed in basements.
Residents told troops they only knew the torture chambers were there because they could hear the screams at night.
"We found numerous houses, also, where people were just chained to a wall for extended periods of time," said U.S. military intelligence officer Major Jim West.
Marines believe they found the place where British hostage
Forensics teams are testing blood on the walls and floors to determine who was held there -- and intelligence officials are hoping interviews with those already in U.S. custody can uncover even more.
Between U.S. and Iraqi forces, more than 1400 people have been detained in connection with the Fallujah operation. But already more than 400 have been let go after it was determined they were non-combatants, reports Cowan.
Officials concede some of the very people responsible for the abductions could be walking the streets again -- planning to restart what had become Fallujah's most notorious industry.
"We've seen a small business grow out of someone who will do the kidnapping and then sell the person they've kidnapped off to one insurgent group or another, basically give them to the highest bidder, " said West, the U.S. military intelligence officer.
It's a cold reality that will stain this city for generations -- whether the insurgents return here or not.