A police surgeon who testified against Pakistani security forces is dead, gunned down by unknown assailants.

Police officials say Baqir Shah was shot and killed Thursday in Quetta. He had conducted autopsies on foreigners who had been killed by police.

Shah had been severely beaten and complained of constant death threats after he ruled Pakistani forces shot and killed a group of five men and women from Russia and Tajikistan earlier this year.

Those in charge of the security team had said the five were suicide bombers who died when they detonated a grenade at a checkpoint near Quetta, the capital of southwestern Baluchistan province. Shah's autopsy found the men and women had actually been shot to death.