ST PETER — Court documents filed with attempted murder charges  suggest a search of Burton Ewing Jr.’s backpack might have provided a red flag that would have kept him at the St. Peter Regional Treatment Center and stopped him from allegedly attempting to kill his mother.

Ewing, 48, made his first appearance in court Thursday. He was arrested at Seven Mile Creek County Park Tuesday while he was stabbing his mother, 69-year-old Marlys Helen Olson of Coon Rapids. He is facing five felony charges, including first-degree attempted murder and first-degree assault. His bail was set at $1 million.

The criminal complaint describes a brutal attack that was first witnessed by people at the park and was still taking place when Nicollet County Sheriff’s deputy Jared Thelemann arrived at about 6:15 p.m. Thelemann said Olson’s car, a PT Cruiser, was rocking back and forth when witnesses in the park’s parking lot pointed him toward it.

Ewing appeared to be stabbing someone when Thelemann got out of his squad car, pulled his gun and confronted him, the deputy reported. As Ewing stepped away from the car, he dropped a knife on the ground.

After backup officers arrived, Thelemann and state trooper Dan Anderson attempted to help Olson. She was bleeding profusely from 22 stab wounds to her hands, head, throat and chest. She was eventually airlifted from the park to the Hennepin County Medical Center in Minneapolis, where she was in critical condition Thursday.

Thelemann arrived quickly because he and other law enforcement officers were already in the area searching for 25-year-old William Daniel Pfeffer Jr., another treatment center patient who had left the facility without permission about two hours before Ewing was allowed to leave. Pfeffer was arrested at the same park Wednesday. Investigators do not suspect the incidents are connected.

After Ewing was arrested and brought to the Nicollet County Jail, he was interviewed by Marc Chadderdon, a Sheriff’s Department detective. Ewing told Chadderdon that his mother had picked him up at the treatment center at about 3:15 p.m. because he had a 10-hour pass. When Ewing left the facility, he had a backpack he had filled with everything that was important to him and enough provisions for three weeks, the complaint said. He also had all of his cash with him.

Ewing and his mother stopped at a store in St. Peter to purchase items they would need while they were together, including a pair of cooking tongs. Olson then drove both of them to the park, which is about five miles south of St. Peter on Highway 169.

As soon as his mother pulled into the parking lot on the river side of the park, Ewing started beating her with a bicycle seat he had brought with him, the complaint said. While she was dazed from blows to the head, he allegedly attempted to kill her by forcing the tongs into her eyes.

The tongs were bending, so he got out of the car, went to the back of the car to get a steak knife Olson had brought with her, then went to the driver side of the car and started stabbing her in the neck, chest and back, the complaint said. Ewing allegedly planned to leave his mother’s body at the park after he killed her. He also allegedly told Chadderdon that his mother did nothing to provoke the stabbing.

Ewing was sent to the Minnesota Security Hospital in St. Peter in 1998 after he beat his sister, Mary Ewing, to death with a hammer at her Shoreview home. He was charged with murder and a Ramsey County District Court judge found he was not guilty by reason of mental illness.

During Ewing’s court appearance Thursday, Nicollet County Attorney Michelle Zehnder Fischer noted that the anniversary of Mary Ewing’s death was Monday, which was the day before the stabbing.

Burton Ewing was transferred to a transition program, also on the treatment center campus, in 2008. In January 2011, he was allowed to move to a residential treatment center in Sauk Rapids with a provisional discharge. He returned to St. Peter fewer than two weeks later after his discharge was revoked and a warrant was issued for his arrest, according to court records.

On Oct. 28 a social worker with the treatment center’s transition program proposed a “therapeutic pass plan” for Ewing. The first day he was allowed to leave the facility with a pass, according to the plan, was Nov. 11.

 Anne Barry, deputy commissioner of human services, said Wednesday that Burton had been issued several day passes before Tuesday’s stabbing.