Barret was arrested on August 6 in a guest house despite being termed persona non grata and expelled in 2011. His arrest over five years ago came a few days after US navy seals killed Al Qaeda chief Osama bin Laden in Abbottabad.
This month, the police and Federal Investigation Agency conducted a joint raid on a guest house the same day he landed in the federal capital on information provided by the airport staff.
A case under Foreigners Act and the Pakistan Customs Act was lodged against him.
Sources reported that Barrett was deported to United States via London through Pakistan International Airlines flight 711.