The prisoner who provided the crucial information was a family member close to the former president, the commander of the US army's 4th infantry division said on Sunday.
Speaking to a news conference, Commander Major-General Raymond Odierno said that US forces have attempted to close in on wanted members of the ousted government by working through family and tribal ties.
"There were a lot of people involved in this ... as we continued to chat to people we got more and more on a family that was considered close to Saddam Hussein".
He said that over the past 10 days US forces were able to question several members from this family.
"Finally we got the ultimate information from one of the individuals," he said.
The information ended an intense manhunt since the fall of Baghdad in April, a US occupation official said on Sunday.
"The most recent final endgame was from one captured person who provided a lead which led them to that location," the official told Reuters on condition of anonymity. The captured Iraqi was not identified.
"Over the past week or two there has been an increased effort to try to identify people who might be enabling him to keep hidden," the official said.
US intelligence agencies and the military launched "an analytic effort devoted to trying to find who from former bodyguards and other supporters might be in a position to help him hide out," the official said.
US forces including Task Force 121 was sent out to search for those supporters who had been identified. "These are not big-time names," the official said.
"Some of them couldn't be found but they could find people who were related to them, or knew them, and as they would scoop up some of these people they would interrogate them and ask them about the whereabouts of the other people they were looking for," the official said.
The hunt for Saddam
4 April 2003
Iraqi television shows recent footage of Saddam walking along a Baghdad street greeting Iraqis.
7 April 2003
Mansur district of Baghdad is bombed after intelligence indicates Saddam and his sons were meeting there. Civilians among the dead.
22 July 2003
Saddam's sons Qusay and Uday, and a grandson are killed in a seven-hour gun battle with US troops.
American forces later raid the northern city of Mosul and announce they missed Saddam "by a matter of hours".
27 July 2003
In Tikrit, three farms raided by US soldiers but military officials say they missed Saddam by 24 hours.
13 December 2003
Saddam is captured by US forces in the town of Al-Dwar, 10 miles south of Takrit.
"And so they kept moving closer and closer to the inner circle," the official said.
"In recent days they picked up a person who in interrogation gave them new sites, which led them to new information that led them to new people, which led them to new sites, which led them to the site they went to last night where they thought that Saddam and or one of his top enablers would be, and it turns out he was," the official said.
Sen. Saxby Chambliss, a Georgia Republican and member of the Senate Intelligence Committee, told Reuters that Saddam had been nearly caught two previous times.
"I know we have been very, very close to capturing him on two previous occasions," Chambliss said in a telephone interview. "We had tips and we just missed him."
The size of the force - about 600 soldiers - sent to capture Saddam showed how confident US forces were that he might be at that site, Chambliss said.
He said it was possible that insurgent attacks on US troops and Iraqi civilians could increase in the short term and that US troops were going to be on "high alert" for the near future.