Special envoy Richard Holbrooke met with the heads of the Pakistani government Tuesday but reportedly did not question Pakistani officials about last week’s release of nuclear scientist A.Q. Khan. Khan helped Pakistan build its nuclear arsenal and later helped smuggle nuclear weapons blueprints to other countries, including Iran, North Korea and Libya. Khan had been under house arrest until last week, when the Pakistani High Court declared him to be a free citizen. The State Department says Khan remains a serious proliferation risk. Pakistan has never let foreign investigators question Khan.