On September 23, 2016, a mass shooting occurred at Cascade Mall in Burlington, Washington, U.S. Five people were killed in the incident.

[6][7] On September 23, 2016, Cetin bought tickets to an evening showing of the movie Snowden at Cascade Mall in Burlington, Washington.

They were Sarai Lara (16), a sophomore at Mount Vernon High School and cancer survivor;[16] Chuck Eagan (61), a Boeing maintenance worker from Lake Stevens;[17] Belinda Galde (64), a probation officer with the Snohomish County District Court;[18] Beatrice Dotson (95), Galde's mother;[19] and Shayla Martin (52), a make-up artist at Macy's.

[21] He graduated from Oak Harbor High School in 2015[22] and worked as a bagger at the Commissary in Naval Air Station Whidbey Island.

[31][32][33] Cetin told authorities that he was interested in the activities of ISIS, but when asked if the terrorist group had inspired his actions he replied, "I can't answer that.

"[8][34] On social media, Cetin posted photos of serial killer Ted Bundy and Islamic State leader Abu Bakr al-Baghdadi.

[35] Cetin had a YouTube channel on which he posted gameplay clips from several video games including Call of Duty: Black Ops II and The Elder Scrolls V: Skyrim, but never expressed intent to commit acts of violence in real life.

[36] On September 25, 2016, reports said that Cetin may have been motivated by the break-up of a relationship with a worker from the Macy's store he targeted, but at the time the ex-girlfriend had not worked there in months and lived in another county.

[37][8] Initial reporting had revealed that Cetin had completed the legal steps to become a voter and had voted three times despite apparently not being a United States citizen.