The suspect in a shooting rampage at a rural retreat for Korean Roman Catholics confessed to killing a woman and injuring three other people, authorities said Tuesday.

John Chong, 69, admitted his involvement during an interview Friday, several days after the April 7 shooting, said Riverside County sheriff's Sgt. Michael Lujan. He said Chong also told investigators that he purchased the .32-caliber revolver in December and practiced using it in the hills surrounding the retreat east of Temecula.

Chong will be charged with one count of murder and three counts of attempted murder in the attack and each count will include an enhancement for the use of a firearm, said John Hall, a district attorney's spokesman.

Investigators say Chong fatally shot a woman at the Kkottongnae Retreat Camp and wounded her husband before another couple disarmed him in a violent struggle after he tried to shoot them as well. Chong suffered severe head trauma in the fight and was initially unconscious.

Lujan said that when Chong came to, he told investigators he was angry with the couples because he felt they didn't contribute enough to the work being done around the camp. Chong and the two couples were all volunteers who lived at the retreat.

"He believed that the victims were not treating him fairly, or at least that was his perception," Lujan said. "His statement was that he's known them over three years and did not agree with the way that they were living their lives."

Lujan said investigators couldn't come up with a more specific motive and Chong did not say that any one event triggered the attack. He was interviewed through a Korean interpreter who is also a sworn sheriff's deputy, Lujan said.

On Tuesday, prosecutors released new details of the deadly attack based on investigators' interviews with the suspect and living victims.

Hall said that Jungpil Yun, one of the victims, told investigators that he and his wife's relationship with Chong had previously gone sour and they hadn't seen him for several weeks before the shooting.

When Chong showed up at their door on April 7, Yun told investigators, the couple invited him in to eat, believing he had come to make amends during the Catholic holy week.

Chong then allegedly pulled out the gun. Chuneui Yun dropped to her knees to pray; Yun tried to push the gun away, but missed, according to Yun's statement. Chong then allegedly shot the 59-year-old man once in the chest and his 58-year-old wife in the head.

Chuneui Yun died from her wounds.

Hall said at the second couple's home, Julina Kim, 65, was on her knees praying in the living room when Chong walked in. Her husband, Joseph Kim, 69, was reading a Bible in a bedroom.

Hall said Chong allegedly kicked Julina Kim several times and fired at her at close range, but she was not hit. Joseph Kim ran in, wrestled the gun away from Chong and struck him over the head with a dumbbell, Hall said.

Chong was transferred from a regular hospital to a jail hospital late Monday and booked for investigation of murder and attempted murder. He was being held on $1 million bail.

The Sheriff's Department hasn't been able to find any relatives of Chong and he had no prior criminal record, Lujan said.

The retreat, run by Korean nuns, is one of four U.S. branches of the Kkottongnae Brothers and Sisters of Jesus, a Roman Catholic organization dedicated to serving the poor and homeless. It was founded in the city of Cheongju, South Korea, by Father Oh Woong Jin in 1976.