A woman charged with murdering a Marine's wife said she strangled the victim to keep her from another Marine who ran a kinky sex ring, according to search warrants unsealed Wednesday. The documents shed light on a possible motive in the killing of 22-year-old Brittany Killgore, whose body was found in April near a Southern California lake. A judge ordered the warrants unsealed at the request of news organizations including The Associated Press. Jessica Lopez said in a seven-page letter that she acted after the victim told her that she had a "whole night planned" with Louis Ray Perez. Lopez, 25, said she then shot Killgore with a stun gun, wrapped a rope around a neck, buried her face in a pillow and strangled her. "She barely moved but she just wouldn't die, the miserable whore," the letter said. Lopez said she made "a few attempts to chop her up" with Perez's power tools and doused the body with bleach to get rid of evidence before dumping Killgore near Lake Skinner. The documents give no indication that Killgore knew about the sex ring and prosecutors have described her as an innocent victim. Detectives said she accepted Perez's invitation to a San Diego dinner cruise after Perez helped her move that afternoon. The warrants do not say how Killgore met the suspects. Killgore was last seen April 13 in a purple evening gown, three days after she filed for divorce from Lance Cpl. Cory Killgore, who was serving in Afghanistan at the time. Lopez wrote that she believed Killgore was trying to come between her, Perez and Dorothy Maraglino. The three suspects all lived together at a home in Fallbrook, north of San Diego. All three have pleaded not guilty to murder. Detectives found what they said looked like a "sex room/dungeon" in the Fallbrook home, with "several bondage type apparatuses; toys and tools." In her letter, Lopez called Perez the "Master" and told police he wasn't responsible for the killing. Detectives found the letter in a San Diego hotel where Lopez was discovered with self-inflicted cuts four days after Killgore disappeared. The letter - below a mirror that was scrawled with the word "PIGS READ THIS" - accused police of "complete incompetence." Sloan Ostbye, Lopez's attorney, didn't immediately respond to a phone message Wednesday. She joined the San Diego County district attorney's office in an appeal to keep the documents sealed.