Before their bloody attack on the French satirical magazine Charlie Hebdo, the two masked gunmen reportedly called out: "Tell the media that this is al-Qaeda in Yemen."
But whether the attackers, who killed 12 people during Wednesday's shooting rampage, belonged to al-Qaeda, another organization or if they acted alone is something Western intelligence officials are still trying to figure out.
An American official told The New York Times on Thursday that one of the suspects, Said Kouachi, 34, traveled to Yemen in 2011 to receive al-Qaeda training and that he spent "a few months" learning "small arms combat, marksmanship and other skills," the newspaper reported.
By Thursday evening, Said Kouachi and his younger brother Cherif Kouachi, 32, who is also a suspect, had not been apprehended by police, despite a massive manhunt by French authorities.
As intelligence officials sift through potential leads and clues, some have suggested that the inclusion of one of the victims, Stephane Charbonnier, on a list of targets published in al-Qaeda's English-language magazine Inspire also suggests the involvement of the terror organization. Charbonnier was the editor of Charlie Hebdo.
#CharlieHebdo cartoonist Stéphane Charbonnier was listed as "wanted" in 2013 issues of AQAP's Inspire magazine pic.twitter.com/7U1YpZlyGN— Jeb Boone (@JebBoone) January 7, 2015
However, some terrorism analysts told Mashablethey were skeptical that al-Qaeda was behind the attack.
"If that was Al-Qaeda, they would have taken credit for it," Mubin Shaikh, a former Taliban recruiter who later became a national security operative in Canada, told Mashable.
While some sympathizers initially tried to claim credit for the attack online, an al-Qaeda representative told the Associated Press that the attack was "inspiring" but said the group was not claiming responsibility for it.
Robert McFadden, Senior Vice President of The Soufan Group which monitors radical groups, was also hesitant to say al-Qaeda was behind the shooting as it doesn't fit the group's usual modus operandi -- "the big splashy" attack rather than "the hit-and-run type of assault," he told Mashable.
The younger brother Cherif, who was convicted in 2008 for trying to recruit people to fight Americans in Iraq, is believed to have been part of a loosely organized group of French Islamic militants.
However, McFadden said formal affiliation with any group is less important than motivation.
"It's not so much the group affiliation that's important but the ideology," he said. The radical rhetoric pushed by al-Qaeda, its offshoots and other groups, including the Islamic State or ISIS, can inspire lone wolf-type of attacks, he added.