Usama ibn Mohammed ibn Awad ibn Ladin (Arabic: 'sm@ bn mHmd bn `wD bn ldn, usamah ibn muhammad ibn 'awad ibn ladin), often anglicized as Osama bin Laden (; March 10, 1957 - May 2, 2011), was a founder of al-Qaeda, the organization responsible for the September 11 attacks in the United States and many other mass-casualty attacks worldwide. He was a Saudi Arabian until 1994 (stateless thereafter), a member of the wealthy bin Laden family, and an ethnic Yemeni Kindite. Bin Laden's father was Mohammed bin Awad bin Laden, a Saudi billionaire from Hadhramaut, Yemen. His mother, Alia Ghanem, was from a secular middle-class family based in Latakia, Syria.
Bush administration
Immediately after the September 11 attacks, U.S. government officials named bin Laden and the al-Qaeda organization as the prime suspects and offered a reward of $25 million for information leading to his capture or death. On July 13, 2007, the Senate voted to double the reward to $50 million though the amount was never changed. The Airline Pilots Association and the Air Transport Association offered an additional $2 million reward.  According to The Washington Post, the U.S. government concluded that Osama bin Laden was present during the Battle of Tora Bora, Afghanistan in late 2001, and according to civilian and military officials with first-hand knowledge, failure by the United States to commit enough U.S. ground troops to hunt him led to his escape and was the gravest failure by the United States in the war against al-Qaeda. Intelligence officials assembled what they believed to be decisive evidence, from contemporary and subsequent interrogations and intercepted communications, that bin Laden began the Battle of Tora Bora inside the cave complex along Afghanistan's mountainous eastern border.  The Washington Post also reported that the CIA unit composed of special operations paramilitary forces dedicated to capturing bin Laden was shut down in late 2005.  U.S. and Afghanistan forces raided the mountain caves in Tora Bora between August 14-16, 2007. The military was drawn to the area after receiving intelligence of a pre-Ramadan meeting held by al-Qaeda members. After killing dozens of al-Qaeda and Taliban members, they did not find either Osama bin Laden or Ayman al-Zawahiri.

Q: When did the Bush administration learn about him?
A: Immediately after the September 11 attacks, U.S. government officials named bin Laden and the al-Qaeda organization as the prime suspects

Q: How did they conclude he was involved?
A: unknown
what was did the bush administration do about him?
offered a reward of $25 million for information leading to his capture or death.
offered a reward of $25 million for information leading to his capture or death.