PARIS (AFP) - A second Frenchman who appeared among Islamic State in Iraq and Syria (ISIS) extremists in a grisly execution video has been identified as a 22-year-old man from an eastern suburb of Paris, a source close to the case said Wednesday.
The source named the man as Mickael Dos Santos, who goes by the name of Abu Othman. He is believed to have left for Syria in the autumn of 2013, and became known to investigators shortly afterwards during a probe into a network channelling extremists into the war-torn country.
"The man concerned is known for his terrorist involvement in Syria and his violent behaviour shown on social networks," Prime Minister Manuel Valls had said, without confirming his identity.
President Francois Hollande earlier confirmed a second Frenchman was spotted in the video and that he originated from Val-de-Marne. He was seen in a video released Sunday by the ISIS group which showed the killing of 18 Syrian prisoners and a US aid worker.
French prosecutors had already confirmed the identity of one man in the video, 22-year-old Maxime Hauchard from Normandy in northern France.
Hollande said it was not clear exactly what role the men played in the beheadings. "The judicial system will have to establish this," he told a news conference during a visit to the Australian capital Canberra.
French Interior Minister Bernard Cazeneuve said in Paris that Hauchard left for Syria "in August 2013 after a stay in Mauritania in 2012", after reportedly becoming radicalised online.
Around 1,000 French nationals are thought to have taken part in the conflict in Syria and Iraq, with 375 currently there, the government has said. At least 36 have died.
Hollande said the issue of foreign fighters and how they were being "brainwashed" was a major concern.
"They could be from any background, from any ethnic origin - but they can easily be brainwashed into becoming converts, and this is a very important matter," he said. "We must be vigilant, and we must be strong."
Earlier this month, Paris adopted an anti-terrorism law which will slap a travel ban on anyone suspected of planning to wage jihad, and Hollande said it was crucial that the full force of the law is used on those opting to fight overseas.
"What is very important is not just reducing the number and avoiding new ones (foreign fighters), but have some sort of penalty applying to those who went to these areas because if you go to a combat zone it is something that should be subject to sanctions and penalties within the law," he said.
Kassig, who took the name Abdul-Rahman after converting to Islam, was captured last year and became the fifth Western hostage beheaded by ISIS after two US reporters and two British aid workers.
Monitoring group the Syrian Observatory for Human Rights said Monday it had documented the execution of 1,429 people in Syria by ISIS in the five months since it declared the establishment of a "caliphate" in areas under its control.