By Peer Muhammad & Shabbir Mir in The Express Tribune, July 1 ISLAMABAD: Gilgit police on Sunday claimed a major breakthrough in the Nanga Parbat shootings after it arrested one of the 16 men believed to be involved in the killing of 10 foreign tourists and their cook on the night of June 21. Deputy Inspector General Police (DIG) Ali Sher, who is leading the investigation, told The Express Tribune via telephone that police raided…