TUCSON, Ariz. » The two girls, ages 12 and 13, stood at a neighbor’s house shortly before 4 a.m. Tuesday and began pounding on the door, knocking frantically on a nearby window. They were barefoot and trembling. The couple inside opened the door and was shocked when the girls told them they had been imprisoned in a home across the way.

One day later, that neighbor was still at a loss. "I didn’t even know there were children living in that home," said Phillip. He and his wife Alice, who declined to give their last name, helped the girls calm down and, although the sisters begged the couple to call their grandmother, Phillip called police.

Tucson police on Wednesday said three sisters — 12, 13 and 17 — had been confined to their bedrooms for many months, where music or a static sound played at all hours and surveillance cameras pointed at their beds 24 hours a day. Sometimes they weren’t allowed to go to the bathroom, forced to relieve themselves in their bedroom closets, police said.

Authorities said that while the family had moved into this Tucson neighborhood only last August, the girls said they had been imprisoned for up to two years in prior homes.

Sophia Richter and Fernando Richter — the girls’ biological mother and stepfather — were taken into custody shortly after police arrived and were booked into Pima County Jail.

The stepfather, 34, was arrested on suspicion of kidnapping, emotional child abuse, physical child abuse and sexual abuse with a person under 15 years of age. The mother, 32, was arrested on suspicion of kidnapping, emotional child abuse and physical child abuse. A judge set their bail at $100,000 and $75,000, respectively. They did not enter pleas.

Phillip said he and his wife opened the door only because the girls were so distraught. "They kept saying their stepfather had a knife and tried to break into their room," he said. "They were also afraid that the mother was going to be killed by their stepfather."

The girls, who told police they had escaped the single-story suburban home through their alarmed bedroom window, appeared unkempt and smelled of urine and body odor, according to Phillip. He also said the girls were worried about their older sister because she was still in the house.

When officers responded to the Richter home, they found the 17-year-old in a locked bedroom with loud hip hop music blaring from speakers facing the bed.

"I can tell you that the music was so loud that she had no idea what was going on around there," Tucson Police Chief Roberto Villasenor said at a news conference Wednesday. "She was totally surprised to see police there."

Indeed, Phillip said he heard loud music whenever the couple was out but had figured they simply wanted to make it appear someone was home so nobody would break in.

The 17-year-old kept a satchel around her neck with a small calendar where she documented in detail the amount of days she’d been confined and even the food she’d consumed, Villasenor said, adding that the girls were fed once or twice a day and were kept in filthy living conditions.

An elaborate alarm system had been attached to the two bedroom doors and the vents were shuttered with duct tape. The space between the bedroom doors and the floor were blocked off with some sort of cloth. "It seemed to be a way of soundproofing the rooms," Tucson Sgt. Chris Widmer said.

Villasenor said the locks to the bedrooms were from the inside and, except for the alarm system, it appeared the girls could have opened those doors on their own.

"But something kept them from doing that," he said. "Until you’ve been in those shoes you really can’t understand. … I will say that they did do things that made these girls feel isolated and made real sure that they didn’t feel like they were in control."

Villasenor said the two bedrooms were monitored with security cameras and that the girls had to signal to the camera if they needed to use the bathroom. A parent would escort each to the bathroom and back through a hallway where a barrier blocked the view to the rest of the house.

There were also times when they were not allowed to use the bathroom, Villasenor said. Investigators found jars of what appeared to be human waste along with piles of clothes contaminated with urine inside a closet.

Relatives never visited because they believed the family was living in San Diego, police said, noting that the mother had a cell phone number with a San Diego area code as part of the alleged ruse.

Villasenor also said the girls had not attended school for the last two years, though the mother said they were homeschooled. Phillip said one of the girls told him, "We’re not allowed to go to school," but described them as polite and articulate.

The three girls are in a group home for the time being. "We didn’t’ want to separate them," Villasenor said. "We made sure they are together."