Boko Haram Leader Abubakar Shekau Reported Killed Again — This Time by Cameroon's Army

Nigerian security forces are investigating reports that Abubakar Shekau, the notorious leader of the Boko Haram extremist group waging an Islamist insurgency in the country's north, has been killed in fighting.

It is by far from the first report of Shekau's death — previous claims of his demise have been put down with sneering proof-of-life videos in which the Islamist commander mocks the inability of his foes to defeat him. But the release of a photo by Cameroon's armed forces purporting to show Shekau's body has attracted particular interest.

The image shows a man lying on the ground, apparently with a wound to his head. The bearded individual bears a close resemblance to Shekau as seen in the many video appearances in which he threatens the Nigerian government and boasts of the strength of the Islamist group which has brought mayhem and bloodshed to a large swathe of the north.

The Cameroonian military posted the picture to social media with no explanation as to the circumstances of the alleged killing. The country's armed forces have been increasingly engaging with Boko Haram along its border as the group makes gains in the state of Borno, north-eastern Nigeria.

Nigerian security forces have been struggling to contain the onslaught from Boko Haram, which has rampaged through towns in the country's north and is increasingly striking at the capital, Abuja, in its bid to carve out an Islamic caliphate — the establishment of which was declared last month in the town of Gwoza. More than 2,000 people were killed in attacks by the group in the first half of 2014, according to Human Rights Watch. Boko Haram has also kidnapped civilians including children for use in the insurgency; the fate of more than 200 schoolgirls abducted from the town of Chibok in April, whom the group later threatened to marry off to fighters, is still unknown.

A source familiar with the Nigerian investigation told Bloomberg that it was thought Shekau may have been killed in fighting near Konduga in Borno state. Nigeria's army said last week that it had killed over 60 Boko Haram fighters and captured a senior leader during a battle at Konduga, which lies around 20 miles from the state capital, Maiduguri. The military said the captured commander, who wasn't identified, was being treated at a military hospital in the area.

Adding to the confusion surrounding the report, some local media suggested the man killed by the Cameroonian military might have been a body double used by Shekau, citing anonymous security sources.

There has been no word as yet from Boko Haram on the claim. But its veracity was questioned by experts, who noted the frequency of such reports.

"Is this his fourth or fifth death? He dies more often than an iPhone battery," Ryan Cummings, a security analyst, said, according to The Times.

Follow Hannah Strange on Twitter: @hannahkstrange