The 20-year-old man accused of shooting and killing five people at a Washington state mall last week reportedly posted a blog with a photo of Islamic State group leader Abu Bakr al-Baghdadi, leading some to believe his alleged rampage was linked to the terror group.

Though his motive was not immediately confirmed, it’s possible the attack is another in a string of attacks in the name of ISIS.

Arcan Cetin, a Turkish immigrant and legal U.S. resident, was arraigned and charged Monday with five counts of premeditated murder after authorities tracked him down following the minute-long shooting at the Cascade Mall in Burlington.

Many reports have said Cetin smirked during his arraignment, during which he was held on $2 million bail, and authorities have yet to rule out whether his attack was inspired by ISIS.

Cetin had two different blogs on micro-blogging site Tumblr that were linked together, and one of those was also linked to his Twitter account, according to the Associated Press. The blogs reportedly showed pictures of the ISIS leader al-Baghdadi and Iranian Supreme Leader Ayatollah Khamanei.

ISIS hasn’t claimed responsibility for Cetin’s alleged shooting, but his supposed link to the terror group is similar to other violent mass attacks that have taken place this year.

Days before Cetin’s alleged attack, Dahir Ahmed Adan allegedly stabbed and injured 10 people at a Minnesota mall with a kitchen knife. In that instance, ISIS reportedly claimed Adan was one of its “soldiers” in a statement on one its news sites, CNN reported. Adan was shot and killed by an off-duty police officer.

The claim and statement have yet to be verified, but the FBI did call Adan’s attack “a potential act of terrorism.”

A shooting at an Orlando nightclub that left 49 people dead and many more injured in June was also linked to ISIS. Shooter Omar Mateen reportedly pledged allegiance to the terror group during the shooting and the ISIS recited a message on its official radio station to claim responsibility, according to CBS News.