Sources said intelligence agencies have released most of the 20 members of various banned terror outfits who were apprehended to probe their links with Shahzad.
They were sent back to their homes on Friday night after they were found innocent.
It is not clear whether Sheik Mohammed Rehan, a top JeM leader, who purportedly drove Shahzad from Karachi to Peshawar in July 2009, was arrested or not.
Pakistan had banned the JeM, the terror group which has close links with the Al Qaeda and primarily targets India, in 2002, but analysts believe that it is receiving continuous help from the Inter-Services Intelligence. Some experts are also of the view that the ISI had actually facilitated the terror group's formation.
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