(CNN) -- Three sisters who were imprisoned for possibly two years in a Tucson, Arizona, home were bombarded by a constant barrage of music or white noise day and night, police said Wednesday.
The psychological torture is the latest allegation in a case that was blown open early Tuesday morning when two of the girls, ages 12 and 13, ran to a neighbor's house to escape their knife-wielding stepfather, Police Chief Roberto Villasenor said during a news conference.
Authorities found the third sister, age 17, locked in a bedroom, he said.
The girls -- who appeared malnourished and extremely filthy -- told investigators that they had been "imprisoned in their bedrooms for at least the last several months and possibly up to two years," according to a police incident report.
Inside the house, authorities allege they found a macabre scene: locked doors with elaborate alarm systems and a video and sound system that allegedly allowed the stepfather and mother to watch the girls while torturing them with a "constant barrage" of music.
The girls' stepfather, Fernando Richter, 34, and the mother, Sophia Richter, 32, were arrested and booked into the Pima County Jail.
Sophia Richter faces three counts of kidnapping, three counts of child abuse/emotional abuse and three counts of child abuse/physical abuse. The stepfather faces the same charges, plus an additional count of sexual abuse with a person younger than 15, according to the report.
Villasenor would not elaborate on the sex abuse charge Wednesday, saying only, "We had enough to charge him with that."
A judge on Wednesday set bond for Fernando Richter at $100,000 and for Sophia Richter at $75,000 after the pair appeared in court via video, according to CNN affiliate KOLD.
The case began to unfold just after 4 a.m. Tuesday, when police responded to a report of a domestic incident involving a knife, according to the incident report.
When police went into the house, they found the 17-year-old locked in her bedroom.
When they opened the door, they were met with loud music that they couldn't hear from the hallway because the room's duct work had been sealed and towels had been shoved under the door, Villasenor, the police chief, said.
"What the kids are telling us, it was 24-7 either loud music or static," Villasenor said.
Cameras were installed in the girls' bedrooms, and if it appeared the girls liked the music, they were then exposed to white noise or static, he said.
The girls were "extremely dirty" and told police they hadn't bathed in at least four months, according to the incident report.
"They were kept in filthy living conditions and allegedly only being fed once a day," it said.
Investigators also found evidence that they were forced to use their bedroom closets as a bathroom, according to the report.
A reporter during the Wednesday news conference told Villasenor that the girls' grandmother accused the three of exaggerating their plight, saying the girls were home schooled and not allowed outside because their parents didn't like the neighborhood.
Several pieces of evidence suggest otherwise, the chief said, citing specifically a journal documenting the last 18 months found in the 17-year-old's satchel. There were also alarms on interior doors and constant video surveillance of the girls' bedrooms, he said.
When the sisters were reunited, Villasenor said, "to the detectives it appeared that they had not seen each other for quite some time."
The neighbors who gave the girls sanctuary the night they showed up asked not to be identified and told CNN affiliate KTVK that they had lived there since August and had never seen any children.
One of the neighbors said the girls "were distraught and visibly shaken. ... They didn't have any shoes on, and they looked like they had just gotten out of bed."
CNN's Chelsea J. Carter contributed to this report.