According to McClatchy News the Bush administration "applied relentless pressure on interrogators" to torture detainees in part "to find evidence of cooperation between al Qaida and the late Iraqi dictator Saddam Hussein's regime." You can find the Armed Services Committee Report here.
In a few words this means the Bush administrtion did not torture simply to secure information "to keep us safe" (a lie for another day). Rather they tortured because they desparately needed to find a link between Sadaam Hussein and al Qaeda because they screwed up on the WMD claim. Think about what this means. Because the Bush administration screwed up and believed what serial liar Ahmed Chalabi and other neo-con "sources" had to say about Iraq they felt that they needed to torture to come up with quick information to justify starting a war in Iraq.