The militant commander and scholar appointed chief of Pakistan's Taliban movement has inherited an organisation that analysts say is in need of a revival having become increasingly fragmented.
Mufti Noor Wali Mehsud immediately became Pakistan's most wanted man when the Tehreek-e-Taliban Pakistan (TTP) announced on Saturday he would succeed Mullah Fazlullah, who was killed by a US drone strike earlier this month.
The appointment of the 39-year-old – known for his religious education and his squint – returns control of the movement to the Mehsud tribe of South Waziristan, where their terror campaign started more than a decade ago.
Militant sources last night said his leadership would have to overcome competing internal factions, and the likely prospect of defections to the patchwork of other extremist groups straddling the border between Pakistan and Afghanistan. The cash-strapped TTP is also struggling to mount operations in Pakistan after fleeing across the border from army campaigns against them.
The group finally announced the killing of Fazlullah more than a week after the first reports of his assassination in an American drone strike on June 13 in Afghanistan's Kunar province.
A group statement said its former emir had been "a person of strong and high determinations and religious beliefs and was headache for the slaves of US in Afghanistan and Pakistan".
Fazlullah became the third consecutive head of the TTP to be killed by a US drone strike, but the group said it was proud its leadership "is being martyred by the head of the infidels".
While Fazlullah rose to power on the back of fiery radio diatribes in his native Swat Valley, Mehsud rose up through the ranks in South Waziristan after fighting for the Afghan Taliban and studying in seminaries.
Considered better educated than his predecessors, as well as acting as a Taliban judge he has also turned to books, last year publishing a 700-page history of Mehsud militants.
A biography included in that book disclosed he had spent months fighting with the Afghan Taliban, firstly against the Northern Alliance north of Kabul in 1996 and then again after the September 11 attacks on the US, in 2001.
After climbing the ranks of the Mehsud Taliban faction and then the TTP in South Waziristan, he took charge of operations in Pakistan's largest city and port of Karachi where his militants ran a kidnapping campaign to raise funds. His book also marked the first claim by the TTP that it had killed Benazir Bhutto at an election rally in December 2007, weeks before she was widely expected to be elected once again as Pakistan's prime minister.
A source in the Pakistan Taliban described Mehsud as "a religious scholar and also the most brave military commander among the TTP leaders".
With the Mehsud tribe making up the bulk of TTP footsoldiers, the leadership had returned to the tribe after four-and-a half years with Fazlullah, the source said. Mehsud's job would now be to reconcile tribal splinter factions.
But a member of one of those factions said an immediate announcement to replace Fazlullah had not been made because the movement was "facing much internal rivalry".
The source said: "The TTP is weak and there is fear of more splits due weak central command. Every unit is working independently and not listening to their central leader."
The winners of any further disputes are likely to be other militant groups, particularly the regional franchise of ISIS.
Saifullah Mahsud, president of the FATA Research Centre in Islamabad, said: "The TTP is a fragmented group. There's no central command as such. The fact is that most of the factions that go to make up the TTP operate independently of each other."
"There's been a steady stream of TTP abandoning it and joining ISIS. That's what ISIS is made of largely, former TTP members.
"I wouldn't be surprised if some of the people from Fazlullah's group switched to to go to Islamic State, rather than accept the leadership of Noor Wali."
Mehsud's years fighting with the Afghan Taliban mean he apparently enjoys good relations with the groups, several sources said. That in itself could pose problems, a member of another militant group with close ties to the TTP predicted.
"The TTP will further split into minor groups because the newly nominated emir is close to the Afghan Taliban, while many of the fighters have sympathies with ISIS. The TTP is very weak financially which is another reason for their splits."