An image grab made on November 17, 2014 and taken from a propaganda video released on November 16, 2014 by al-Furqan Media allegedly shows members of the Islamic State jihadist group, with among them a jihadist believed to be French citizen Maxime Hauchard (R), also known as Abu Abdallah al-Faransi, before taking part in the beheadings of at least 18 men described as Syrian military personnel. AFP/Getty Images

On Sunday, the Islamic State released video of the beheading of Abdul-Rahman Kassig, previously known as Peter, a U.S. aid worker. Kassig is the fifth Western hostage and third American who have have been killed by the extremist group that controls large areas of Iraq and Syria. His death was a blow for many around the world, including not only Kassig's family and friends, but also anyone who cared about the humanitarian ethos that brought the young man to Syria.

For the French, however, it brings a special anguish: The murder may involve one of their own. Interior Minister Bernard Cazeneuve told reporters on Monday that there was a “strong presumption” that a French citizen was one of the executioners in the video, which also featured the killings of more than a dozen Syrian soldiers. In particular, authorities were looking at Maxime Hauchard, who was born in 1992 in the department of Eure in northwestern France, though French media are also reporting that a second French citizen could be involved.

Hauchard converted to Islam at the age of 17 and first became known to French authorities in 2012 when he traveled to Mauritania for "religious education," according to the Interior Ministry. When he returned last year, French authorities opened a preliminary investigation against him on suspicion that he might be planning terrorist acts.

In 2013, Hauchard traveled to Turkey where he said he wanted to work on a humanitarian mission. He then headed toward Syria, joined the Islamic State and assumed the name Abou Abdallah al-Faransi, according to French investigators: Al-Faransi can be translated as "The Frenchman." This summer, French investigators issued a search warrant for Hauchard.

In July, Hauchard gave an interview to France’s BFM television in which he explained how he got to Syria. "I took a flight for 162 euros [$200] which was pretty cheap," Hachard said of his arrival in Turkey. "At the security check they opened my bags, looked at it; I smiled and they smiled back. I had the beard and military boots in it, so I wasn't trying to hide anything."

"We're waiting with joy to go," Hauchard said. "When we hear about a brother who dies, when we hear of him dying as a martyr, it pleases us because he dies as a martyr."

Hauchard has appeared in a number of propaganda videos for the Islamic State, but those who knew him in France are said to be surprised that he could be linked to Kassig's murder. On Monday, the BFM broadcast an interview with Hauchard's uncle who said he did not believe his nephew was involved: "That's not my nephew who cut the head off; that's impossible."

Pascal Hauchard went on to say that his nephew had been quiet but "always nice," adding that he had "never been in trouble with the police."

Analysts believe that hundreds of French citizens have traveled to the Middle East to fight in the ranks of extremist groups: The Interior Ministry put the number at nearly 900 earlier this summer, one of the highest figures among European nations. In an interview with Le Figaro on Monday, French terrorism expert Thibault de Montbrial pointed out that the growing number of people converting to Islam was an indication that "young French suffer from an identity crisis which has existed for many years," though he cautioned that conversion does not have to be a sign of radicalization.

The latest video released by the Islamic State is unusual in that it showed a number of the group's members without masks. In fact, only the British militant, referred to as "Jihadi John" in the British media, kept his face covered, the BBC notes. Another person in the video was initially identified as Nasser Muthana, a 20-year-old from Britain, though his family now denies it is him.

Peter Kassig, the U.S. aid worker beheaded by Islamic State militants, was remembered Sunday for his devotion to helping Syrians. President Obama praised Kassig as a humanitarian killed in "an act of pure evil." (Reuters)