A man believed to have fatally shot five people last year at a shopping mall in Washington state has died in jail.

Arcan Cetin, 20, died in custody Sunday night, according to the Skagit County prosecuting attorney.

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It was not immediately clear how Cetin died.

Cetin was in court in January facing potential death penalty charges.

According to charging documents, witnesses at the Cascade Mall in Burlington saw Cetin remove a rifle from the trunk of his blue four-door sedan, which was reported as either a Kia or a Hyundai. Police later learned from Cetin’s father that he drove a blue Chevrolet Cavalier.

Police said Cetin entered the Macy’s women’s department through the west entrance. He was inside the mall for about a minute during the shooting spree, investigators said.

Cetin shot 16-year-old Sarai Lara near some clothing racks, then walked toward the cosmetics counter. He encountered victim Chuck Eagan, then shot three other women, police said.

Police said Cetin placed the rifle on top of the cosmetics counter, left Macy’s through the west entrance and got into his vehicle.

According to charging documents, “Cetin said that it was him in the video and he did bring the rifle into Macy’s and shot all five victims."

Video showed his vehicle traveling north on South Burlington Boulevard near Cascade Place. The vehicle was last seen on video near South Burlington Boulevard near West Fairhaven Avenue.

Cetin was from Oak Harbor and graduated from Oak Harbor High School in 2015. Family told KIRO7 that Cetin had mental health issues.

Acquaintances said Cetin had been working at the commissary at the Naval Air Station on Whidbey Island.

>> Check KIRO7.com for the latest on this developing story