“Belmokhtar has been active in political, ideological and criminal circles in the Sahara for the past two decades,” Jon Marks, an academic at the London-based think-tank Chatham House, told the BBC.
Born in Ghardaia in eastern Algeria in 1972, Mr Belmokhtar – according to interviews posted on Islamist websites – was attracted as a schoolboy to waging jihad.
He is one of the best known warlords of the Sahara”
Stephen Ellis, Academic
Inspired to avenge the 1989 killing of Palestinian Islamist ideologue Abdullah Yusuf Azzam, he travelled to Afghanistan as a 19 year old to receive training from al-Qaeda.
“While there, Belmokhtar claims [on Islamist websites] to have made connections with jihadis from around the world,” says the US-based Jamestown Foundation, in a report published on its website.
“Moreover, Belmokhtar claims to have been to battlefronts ‘from Qardiz to Jalalabad to Kabul’.”
When he returned to Algeria in 1993, the country was already in the throes of conflict after the French-backed Algerian military annulled elections that the Islamic Salvation Front (FIS) was poised to win.
Mr Belmokhtar joined the conflict, which claimed hundreds of thousands of lives, and became a key figure in the militant Armed Islamist Group (GIA) and later the breakaway Salafist Group for Preaching and Combat (GSPC).
‘Frog-marched’Algerian journalist Mohamed Arezki Himeur says Mr Belmokhtar lost his left eye in fighting with government troops in the 1990s and now wears a false eye.
“He has been condemned to death [by Algeria's courts] several times,” he adds.
When the GSPC merged with al-Qaeda in the Islamic Maghreb (AQIM), Mr Belmokhtar headed an AQIM battalion in the desert between Algeria and Mali.
After AQIM stripped him of his title as “emir of the Sahel” as a result of in-fighting, Mr Belmokhtar launched the Signed-in-Blood Battalion last year.
The attack on the gas facility was its first big operation, showing that he remains influential despite his marginalisation within AQIM.
“He knows the Sahara Desert very well,” says Mr Himeur.
In recent years, Mr Belmokhtar has gained notoriety as a hostage-taker across the vast Sahara, often demanding multi-million dollar ransoms from Western governments which – along with cigarette-smuggling – finances his jihad.
Former UN Niger envoy Robert Fowler was captured by Belmokhtar loyalists outside Niger’s capital, Niamey, in December 2008.
“We were frog-marched and thrown into the back of a truck… We began our descent into hell – a 1,000km [600-mile] journey northwards, into the Sahara Desert,” he told the BBC.
“I think I know instinctively what they [the latest hostages captured in Algeria] are going through.”
In its report, the Jamestown Foundation says Mr Belmokhtar has been able to operate across borders because of his deep ties to the region.
“Key to Belmokhtar’s Saharan activities has been his strong connections with local Tuareg communities… Belmokhtar is reported to have married four wives from local Arab and Tuareg communities,” it said.
Mauritania’s Sahara Media website reports that after the Malian Islamist group, the Movement for Unity and Jihad in West Africa (Mujao), took control of the northern city of Gao last year, Mr Belmokhtar “joined the administration of the city”.
Last month, the Signed-in-Blood Battalion warned against any attempt to drive out the Islamists from northern Mali.
“We will respond forcefully [to all attackers]; we promise we will follow you to your homes and you will feel pain and we will attack your interests,” the group said according to Sahara Media.
Last June, Algerian media reported that Mr Belmokhtar – described in 2002 by French intelligence sources as “uncatchable” – had been killed in clashes between Islamists and Tuareg separatists in northern Mali.
But this turned out to be untrue, with Mr Belmokhtar still a kingpin in the region.
“He is one of the best known warlords of the Sahara,” Stephen Ellis, an academic at the African Studies Centre in Leiden in The Netherlands, told Reuters.