Ever since the 13 November attacks, Abdelhamid Abaaoud has been identified as the man who co-ordinated the triple gun and bomb onslaught on the Stade de France, the Bataclan concert hall and the Paris cafes and restaurants.
But Abaaoud died in a police raid the following week in Seine-Saint-Denis and there has always been a suspicion that he was more of a participant than the chief organiser.
Now US-based terrorism research centre TRAC identifies Frenchman Salim Benghalem as the real ringleader behind the atrocities that claimed 130 lives.
Who is Salim Benghalem?
Early in January, a Paris court sentenced Benghalem, who left for Syria in 2013, to 15 years in jail in absentia.
A notorious jihadist convicted of recruiting others to so-called Islamic State (IS), he has long been known to French authorities and is widely implicated in other attacks on French soil.
In September 2014 he was cited on a US list of 10 Designated Global Terrorists (SDGT).
"Salim Benghalem is a Syria-based French extremist and ISIL member, who carries out executions on behalf of the group."
Wasn't Abaaoud the ringleader?
The true nature of Abaaoud's role in the Paris attacks has never been clear. In the aftermath of the atrocities he was identified as the ringleader and Belgian authorities had for months tried to track him down on suspicion of co-ordinating a terror cell in Belgium.
French authorities implicated him in four out of six foiled attacks in the months leading up to November.
A propaganda video of nine of the Paris attackers either in Syria or Iraq circulated by IS is also preceded with a rant by Abaaoud, so he is clearly being promoted as a major player.
But French authorities have long suspected that the plot must have emanated from Syria and TRAC Director Veryan Khan agrees.
"Abaaoud was the on-site coordinator but according to our sources didn't have control of the capacity to carry out a very professional attack on such a scale," she told Belgian newspaper De Morgen (in Dutch).
And would the ringleader have taken part in the bar and restaurant attacks himself and endured such an ignominious end? In the four days after the murders he is said to have lived hidden in undergrowth beside a main road. Eventually he emerged with the help of his cousin and both died when police raided their flat hours later.
So is Benghalem a more likely ringleader?
He certainly has a higher profile than Abaaoud.
Within a month of the January 2015 Paris attacks, Benghalem appeared on an IS propaganda video from Syria praising the killers and appealing to others in France to launch attacks as "lone wolves".
Benghalem had known all three attackers while being part of the radical Islamist Buttes-Chaumont group in Paris. They had followed similar routes from low-level delinquency to violent jihadism.
Benghalem was radicalised while serving time in jail for attempted murder and is thought to have come under the influence of the group's leader, Mohamed El-Ayouni. Later, he became friendly with the two Charlie Hebdo killers, Said and Cherif Kouachi, and kosher supermarket gunman Ahmedy Coulibaly.
He joined one of the Kouachis and Coulibaly in a botched attempt to spring a Paris Islamist from jail in 2010 and is thought to have travelled with Cherif Kouachi to Yemen in 2011 where both came under the influence of Anwar al-Awlaki, then leader of Al-Qaeda in the Arabian Peninsula (AQAP).
By 2013 he was in Syria earning a reputation for Islamist brutality.
Benghalem's other terror links
Benghalem also forged a friendship in Syria with another Islamist, Mehdi Nemmouche, the man on trial for four murders at the Brussels Jewish museum in May 2014.
The pair had acted as jailers for four French hostages held in Aleppo between July and December 2013.
One of the four, Nicolas Henin, described how Nemmouche had tortured Syrian prisoners and mistreated him too.
But one source told French media that Benghalem was in charge. "When Nemmouche struck, it was Benghalem asking the questions,"
Could Benghalem have plotted the 13 November attacks?
French intelligence are said to believe he may be part of an IS "police force", taking part in executions and corporal punishment, according to Le Monde, as part of a self-styled Islamic Tribunal near Aleppo.
It would make sense that the Paris plot was hatched and supervised in Syria but Benghalem does not appear to be linked to the November attackers in the way he was close to Coulibaly and the Kouachi brothers.
More individuals are yet to be exposed. Ominously, the EU's police agency Europol has now warned of similar potential plots in other European cities with the main purpose being "mass casualties".
If Salim Benghalem was behind the November atrocities in Paris, he may not be alone.