PORT ORCHARD, Wash. (AP) — The Kitsap County prosecutor said he won’t file charges against corrections officers involved in last year’s death of a mentally ill murder suspect at the jail.

Prosecutor Chad Enright wrote in a memorandum that Sean Howell’s death could not be ruled “justified,” as that requires intent to kill, the Kitsap Sun reported.

“The evidence, instead, leads to the factual conclusion that Howell was unintentionally killed when corrections officers attempted to subdue and restrain him,” Enright wrote. “If a person accidentally kills another while engaging in the lawful use of force, the killing is excusable, not justifiable.”

A Washington State Patrol-led investigation by the Kitsap Critical Incident Response Team found that the sheriff’s office had failed to train corrections officers to properly use the “restraint chair” cited in Howell’s death. Investigators noted that restraint chairs — like the SureGuard chair used in the jail — had been linked to inmate deaths across the country.

Sheriff Gary Simpson said an assessment of jail practices is underway by the Clark County Sheriff’s Office.