The officer was supposed to be watching inmates as they filed out of the Monroe Correctional Facility's prison chapel on Jan. 29. In his absence, inmate Byron Scherf was able to re-enter the chapel, where he's accused of strangling officer Jayme Biendl.
Officials believe the guard was still on prison grounds, documents released at the request of The Daily Herald show.
He said he was helping with pat-down searches and talked with two other guards, but the documents state that neither remembers seeing him.
The documents indicate that prison Superintendent Scott Frakes told the officer he "severely compromised an essential safeguard" for Biendl and an inmate "took full advantage of your failure."
Scherf, 53, is charged with aggravated first-degree murder and could face the death penalty if convicted.
The three officers who were fired are appealing their terminations. It's unclear whether they could face criminal charges. The newspaper did not include the names of the fired officers.
The Monroe complex includes five prisons on one campus. About 25 miles northeast of Seattle, it's the state's largest prison and houses more than 2,500 offenders. Biendl worked inside the Washington State Reformatory, a medium-security prison, now more than a century old.
Since Biendl's slaying, the prison says it has increased training, changed staffing and improved how inmates are classified.
Scherf was serving a life sentence. His file contained warnings that his criminal history and indicated he could present a grave risk to corrections officers, particularly women.
Officers also are being outfitted with personal alarms designed to better alert colleagues to problems. The overall inmate population at the reformatory was reduced to 630, from around 750.
Another officer who was fired is accused of failing to verify with Biendl that the chapel was clear of all inmates. He was fired for allegedly making a false entry in a log book indicating the chapel had been checked by Biendl and was empty. After the killing, the officer presented an initial incident report, indicating he saw Biendl close the gate outside the chapel. He later told investigators he wasn't sure.
"Despite what you entered in the logbook, Officer Biendl did not close the gate, did not make notification that the chapel was clear," Frakes wrote in the documents.
The third fired officer submitted an incident report saying he inspected and secured the chapel after Scherf turned up missing in an inmate count.
The officer found Scherf sitting in a chair within feet of the chapel's front doors at 9:19 p.m., Frakes said, adding that Biendl's body was not discovered until 10:26 p.m., after others in the prison realized she had not left work after her shift ended that evening.
After being confronted with video surveillance during a June interview with investigators, the officer acknowledged he did not inspect the chapel, the documents state.
"I wrote down what was expected of me, not what I did," he said.
Four other corrections officers also faced discipline that included demotion or reprimands.