Abu Bakr al-Baghdadi, the head of the Islamic State of Iraq and the Levant (ISIS), has been careful to reveal little about himself and his whereabouts.
Before appearing in a video delivering a sermon in Mosul in July, there were only two authenticated photos of him.
Even his own fighters reportedly do not speak about seeing him face to face.
The ISIS chief also appears to wear a mask to address his commanders, earning the nickname "the invisible sheikh"
But Baghdadi - a nom de guerre, rather than his real name - has good reason to maintain a veil of mystery, says the BBC's Security Correspondent, Frank Gardner.
One of his predecessors, Abu Musab Al-Zarqawi who headed the most violent jihadist group in Iraq until his death, was a high-profile showman whose secret location was eventually tracked down. He was killed in a US bombing raid in 2006.
Baghdadi is believed to have been born in Samarra, north of Baghdad, in 1971.
Reports suggest he was a cleric in a mosque in the city around the time of the US-led invasion in 2003.
Some believe he was already a militant jihadist during the rule of Saddam Hussein. Others suggest he was radicalised during the four years he was held at Camp Bucca, a US facility in southern Iraq where many al-Qaeda commanders were detained.
Before appearing in a video delivering a sermon in Mosul in July, there were only two authenticated photos of him.
Even his own fighters reportedly do not speak about seeing him face to face.
The ISIS chief also appears to wear a mask to address his commanders, earning the nickname "the invisible sheikh"
But Baghdadi - a nom de guerre, rather than his real name - has good reason to maintain a veil of mystery, says the BBC's Security Correspondent, Frank Gardner.
Baghdadi is believed to have been born in Samarra, north of Baghdad, in 1971.
Reports suggest he was a cleric in a mosque in the city around the time of the US-led invasion in 2003.
Some believe he was already a militant jihadist during the rule of Saddam Hussein. Others suggest he was radicalised during the four years he was held at Camp Bucca, a US facility in southern Iraq where many al-Qaeda commanders were detained.
