Police are poring over a journal they say a 17-year-old girl kept while she and her two younger sisters were imprisoned by their mother and stepfather for up to two years.

Tucson Police Chief Roberto Villasenor said investigators were combing through the diary Wednesday for evidence as they build a criminal case against the 32-year-old mother and 34-year-old stepfather.

He declined to reveal the diary's contents but said the teen kept one of her most prized possessions — a photo of singer Enrique Iglesias — in the journal, which was kept inside a satchel.

"It did contain a lot of information that I feel will be useful in helping us to determine the method and length of the imprisonment," Villasenor said.

Investigators said the two younger girls, ages 12 and 13, escaped through the window of the bedroom they shared and alerted a neighbour Tuesday after the stepfather tried to break down the room's door and was brandishing a knife.

Malnourished, no bathing for up to 6 months

Police later discovered the 17-year-old was being held separately from her sisters in another room. The three girls were malnourished and dirty and told officers they hadn't taken a bath in up to six months.

Investigators were trying to determine the last time the girls attended a school. No schools in the area had a record of them, Villasenor said, and police haven't been able to verify the mother's claims that the children were home-schooled.

The girls' accounts of being held in captivity were consistent, Villasenor said. They are now together at a group home in the custody of a state child welfare agency.

A judge set bail of $100,000 for the stepfather, Fernando Richter, and $75,000 for the mother, Sophia Richter, at their initial court appearances Wednesday. They face multiple counts of kidnapping and child abuse, and the Fernando Richter also faces one count of sexual abuse.

The brief court appearances made by video did not include entering pleas, and it wasn't immediately clear whether the man and woman had lawyers.

Aunt barred from contacting girls

The girls' maternal aunt, Chame Bueno, said outside of the court hearing that the mother had said the family was living in San Diego when they actually were in Tucson and wouldn't let her speak with her nieces on the phone.

Bueno, 34, said the stepfather was mentally abusive toward his wife.

"She always talked him up, 'Oh well he pays for all my kids' clothes and he takes them here and he takes them to eat and do this' — and all that time being locked up in a room," Bueno, of Tucson, told The Associated Press. "And he hasn't done nothing she said. She has just been lying."

Villasenor said there were motion sensors on the doors to the girls' bedrooms and video cameras trained on their bed. If the girls needed to use the bathroom, there was an unspecified signal for them to let the parents know they needed a bathroom break.

There were locks on the girls' bedroom doors, the police chief said, but another method, which he declined to reveal, was used to keep the girls from escaping.

Music blared loudly and constantly from the girls' bedrooms, and duct work was sealed and towels were forced against doors to prevent the sound from being heard outside, Villasenor said.

Police were investigating whether the girls had also been imprisoned in a home in Catalina, about 30 kilometres north of Tucson, where the family lived previously.

The mother agreed to speak with investigators but Villasenor declined to provide details of what she said. The stepfather declined to speak with investigators, according to the police chief.

Villasenor said police made a few prior visits to the family's home, but none pertained to the children being held in captivity.

A resident who has lived in the neighbourhood for about five years told the Arizona Daily Star that she didn't know anyone was living in the home, which is set back from the street.

The woman said there was no visible activity at the house, but other neighbours had told her that they had heard what sounded like children playing inside the house at night.