Mehsud, then the most feared man in Pakistan, asked for safe passage for his fighters.
Mehsud's second wife was one of two people killed in the strike, according to the sources.
CNN: Pakistan Taliban leader's wife dies in suspected drone attack
Lieutenant-Colonel Tabraiz Abbas, just in from fighting the Mehsud militants, describes finding Indian-made arms on the battlefield.
The army operates more or less freely on the frontier but is reluctant to touch Mr Mehsud.
But the British had a similar view of the Mehsud to Mr Khan.
Umar was recently in the media spotlight contradicting U.S. officials' contention that Mehsud had been killed in a drone strike.
Last week, Umar told CNN that Mehsud is alive, but ill, and would speak to reporters when he feels better.
The most likely first target is the head of the Pakistani Taliban, Baitullah Mehsud, whose stronghold is in South Waziristan.
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Mr. Rehman was seen as a rival to the leader of the TTP, Hakimullah Mehsud, known for being even more radical.
Mehsud and other key leaders of the Pakistani Taliban have been targeted by the ongoing Pakistani military operation in northwest Pakistan.
CNN: Pakistani Taliban leader may be dead after U.S. drone attack
Other media reports have quoted another spokesman for the group as saying Mehsud is dead and a mourning period is under way.
Their warrior mullahs included Mullah Powindah, an Afghan-backed Mehsud, who in 1894 led an attack on the British team demarcating the frontier.
The chief of the Pakistani Taliban in Karachi, Khan Zaman Mehsud, recently fled to Waziristan, Mr. Aslam, the counterterrorism police officer, said.
The army is now planning a ground attack on the Mehsud militants.
Mr. Rehman was considered by some analysts to be more moderate and more amenable to peace talks than the group's leader, Hakimullah Mehsud.
Despite the almost permanent state of war between the Wazirs and the Mehsud, these commanders forged an alliance with Baitullah Mehsud last February.
Leading a group of Marwat elders, Mr Kamal sat on a blanket with Mehsud, both sides backed up by hundreds of militiamen keeping wary watch.
Majeed said Sunday that he announced the details about Mehsud's connection to the attack because Pakistan could formally charge him at a later date.
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Some 200, 000 Mehsud tribesmen are expected eventually to flee the fighting.
Blamed for the 2007 assassination of former Prime Minister Benazir Bhutto and other terrorist attacks, Mehsud and other Pakistani Taliban are enemies of the democratic government.
This time, however, "there are increasingly strong indications Mehsud is, in fact, dead, " according to a U.S. counterterrorism official, who was not authorized to speak on the record.
CNN: Pakistani Taliban leader may be dead after U.S. drone attack
Ispahani described Mehsud as "a murderer and a monster" and said his death would be a boon to Pakistan's ongoing military operation against Taliban militants inside its borders.
CNN: Pakistani Taliban leader may be dead after U.S. drone attack
Mullah Nazir is also one of only three top level Pakistani Taliban commanders to have been killed by a drone, the others being Nek Mohammad and Baitullah Mehsud.
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Mehsud rarely gave news conferences or appeared before the media.
The two were identified as Commander Saif Ullah, described by police as the right-hand man of Pakistani Taliban leader Baitullah Mehsud, and Maulvi Umar, the well-known spokesman for the group.
It said Bhutto's assassination was orchestrated by Baitullah Mehsud, the leader of the Pakistani Taliban who has ties to al Qaeda -- a conclusion that the CIA came to as well.
U.S. and Pakistani government officials have said they are confident that Mehsud was killed in a suspected U.S. drone strike on his father-in-law's house in the South Waziristan tribal region earlier this month.
Standing among scores of men accepting free blankets and clothes from the Pakistan military, Liaqat Ali Mehsud, a teacher, said the road is so good that he's forgotten that his home was destroyed.
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His indulgence does nothing to undermine the United Kingdom's or the United States' common efforts to find, interrupt, interrogate, and occasionally-as we saw in Pakistan last week with the demise of Baitullah Mehsud-kill a terror mastermind.
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