The Taliban fighters in northwest Pakistan, a senior leader reached by telephone in Orakzai Agency and a local Taliban fighter in Waziristan, said that Mr. Mehsud had been receiving kidney treatment from a relative in his father-in-law’s house in the remote village of Zanghara when the building was struck by missiles fired from a remotely-piloted drone…

“Taking Mehsud off the battlefield would be a major victory,” an American counterterrorism official said Thursday. “The world, and certainly Pakistan, would be a safer place without him.”

Mr. Mehsud, a diabetic, had been sick for some time and had come to his father-in-law’s house for a drip treatment by the relative, who was a medical practitioner, the Taliban fighters said…

Pakistani officials said Mr. Mehsud was visiting his wife in the upper portion of a house when it was hit, though his supporters did not confirm that version of events.

The Taliban, consistent with its standard procedure, threw an immediate cordon around the site of the missile strike, but the cordon was about three miles, wider than usual. No one was allowed either to enter or leave the area, Pakistani officials said. One security official cited conversations with unidentified sources in the area of the strike who said that Mr. Mehsud had been buried secretly and that associates of Mr. Mehsud had confirmed his death. The security official said he believed the funeral had been held in Nargosai, a village in the Zanghara area.