Los Angeles, California (CNN) -- Police say one thing was clear when authorities showed up at a house in Arizona looking for a California girl who had been missing for seven years. The family inside was hiding something.

They were "evasive and untruthful," said Capt. Patrick Maxwell of the Los Angeles County Sheriff's Department's Norwalk Station.

When family members were asked to produce a birth certificate or adoption papers for Amber Rose Nicklas, they could not. Maxwell says that is when they admitted the 7-year-old girl was not theirs.

The child had been missing since September 2003. She was in the care of foster parents in Norwalk, California, when she was snatched by three of her aunts. Two of the aunts were caught at the time but a third got away with the infant.

Maxwell says it appears Amber had been living with the same family in Phoenix, Arizona, for most of the time she was missing, but police are still investigating how she ended up with people who are not her biological family.

Authorities got a tip that Amber could be at a home in Phoenix and went there with a court order Wednesday afternoon.

When investigators tried to serve the court order, they found that a woman in the home had hidden the child in a shower under a pile of clothes and towels, said Phoenix police Sgt. Trent Crump.

Amber's identity had been changed, including her name and date of birth, police said.

Authorities confirmed Amber's real identity through footprints, photographs and DNA swabs. The child is in state custody in California and prosecutors will file charges, Crump said.

CNN's Nick Valencia and Sonya Hamasaki contributed to this report.