By Alexis Akwagyiram and Julia Payne
ABUJA (Reuters) - If Chadian President Idriss Deby is to be believed, Abubakar Shekau, the bearded and bandoliered leader of Islamist militant group Boko Haram, is no more.
Given the many previous reports of Shekau's demise, followed soon after by videos of him brandishing automatic weapons and spouting invective against the Nigerian state, analysts and diplomats are treating the claims with caution.
However, two factors are spicing up the normal guessing game that swirls around the leadership of the notoriously opaque group, which has killed thousands of people in its six-year campaign to establish an Islamic caliphate in northeast Nigeria.
First, Shekau - not known for being camera-shy - has not appeared on video for six months, raising the possibility that he has indeed been injured or killed by offensives during that time by Nigerian, Chadian and Cameroonian troops.
And second, Deby has identified a successor.
Although little is known about the replacement, identified by Deby as Mahamat Daoud, it suggests that even if Shekau is not down and out, he may have a rival for control of an organization long suspected of being riven by factional divisions.
Besides the battlefield setbacks Boko Haram has suffered, disagreements over whether to entertain negotiations with Abuja or declare allegiance to jihadist groups such as Islamic State in Syria and Iraq are believed to have deepened those rifts.
"Boko Haram has always been something of a constellation of units, with its hardline leadership having only limited control or influence over some fighting units," said Roddy Barclay, senior Africa consultant at Control Risks.
"Regional military pressure is likely to have fragmented militant command structures, though it remains uncertain whether a change in leadership has actually occurred."
"HEAD CUT OFF"
The possibility remains that Deby, a wily regional operator who came to power in a 1990 military coup and who has survived several armed attempts to remove him, is trying to engineer internal blood-letting by promoting one faction over another.
"We have cut off Boko Haram's head," said Deby, who has turned Chad's fight against Boko Haram into a personal duel with Shekau. "I think Boko Haram will be finished by the end of 2015."
The new leader Daoud was open to the idea of talks with Abuja, Deby added.
What little is known about Daoud suggests he and Shekau do not see eye to eye, especially on the issue of the extreme violence that Boko Haram has meted out under Shekau's leadership, diplomats and analysts said.
"It may be a tactic to sow disunity within Boko Haram," one Abuja-based diplomat said. "This man, Daoud, has not been fighting or close to the Shekau group. He's more of a learned cleric."
Nigerian security analyst Fulan Nasrullah concurred, saying he understood Daoud to be around 38 years old and the son of an Arab man and Chadian mother renowned for his Islamic scholarship and loyalty to tenets laid down by sect founder Mohammed Yusuf.
Yusuf's largely peaceful movement advocating sharia law and Islamic schooling -- Boko Haram means "Western education is forbidden" in the local Hausa language -- turned violent in 2009, and quickly morphed into a full-on insurgency after Yusuf's death in police custody.
Since then, thousands have been killed and more than a million displaced by the militants who at the start of this year controlled an area the size of Belgium. Much of that territory has since been retaken by Chadian and Nigerian forces.
Nasrullah said Daoud had a significant support base and could bring hundreds of fighters with him if he jumped ship -- as well as vital information about Boko Haram's workings and the whereabouts of its top commanders.
"He could expose the money generation and transfer methods the group uses, reveal critical intelligence about the group's inner structure, and maybe even offer up information as to how to kill Shekau," he said.
"If Daoud is really seeking negotiations, the Nigerian government should hurry and take the offer as having him on side could well be a game-changer."
Shekau's last video appearance was in February, when a person claiming to be him -- analysts believe he may have impersonators -- threatened to disrupt presidential elections held the following month.
The group has released at least five videos since then, none purporting to show Shekau.
However, one source in the office of Nigeria's National Security Adviser played down Shekau's absence from the videos, and remained skeptical of Deby's assertion that Shekau is dead, saying he "wouldn't make too much of that statement".
Femi Adesina, a spokesman for President Muhammadu Buhari, who came to power in March on promises of, among other things, tackling Boko Haram, said Abuja was open to talks if any faction with significant influence came forward.
"If genuine leadership of Boko Haram approaches the government for negotiation, the government will negotiate with them," Adesina said.
(Additional reporting by Isaac Abrak and Felix Onuah in Abuja and Angela Ukomadu in Lagos and Matt Bigg in Accra; Writing by Alexis Akwagyiram; Editing by Ed Cropley and Peter Graff)