American citizen Gary Brooks Faulkner, who arrived in Pakistan earlier this month with a greed to collect a big bounty for killing al-Qaeda chief, has been released and left for the United States, local media reported on Wednesday.

Faulkner, 51, was arrested from the northern Pakistan's scenic city of Chitral on June 15 while attempting to sneak into Afghanistan's Nuristan province.

Caught being armed with pistol, sword, dagger and night vision device, the American has confessed to be on a personal mission of killing al-Qaeda chief Osama bin Laden, having a 25 million U.S. dollar head-money on him, local police said.

Mumtaz Ahmed, a senior police investigator, said Faulkner was hunting bin Laden because he suffered personal losses in the Sept. 11, 2001 attacks.

An intelligence official in Chitral, who asked not to be identified, said Faulkner shouted "Don't come closer to me or I'll open fire!" when approached.

Local media said it marks one of the first instances of an American entering Pakistan and Afghanistan on his own to fight against al-Qaeda and other militants.

Chitral is a tourist destination but had minutely felt the effects of militancy and extremism that have gripped the northwest tribal areas of Pakistan for years.

In April, a Greek social worker and archaeologist, Athanassios Lerounis, was safely recovered after being kidnapped by Taliban militants in September 2009 to exchange freedom of some militants and taken to Nuristan in the neighboring war-torn Afghanistan.