North Carolina police have released the recording of a 911 call that Zahra Baker's father made to authorities reporting that the 10-year-old girl was missing -- claiming that she had been mistaken for another girl in a ransom ploy.

Adam Baker told a Hickory Police Department dispatcher on Oct. 9 that a ransom note was found indicating that someone kidnapped his boss's daughter after someone set a fire in his backyard.

"The police were out here last night and found a ransom note for my boss's daughter. It appears they took my daughter instead of my boss's daughter," Baker said in the 911 call. He says in the note that the kidnappers were going to come for his boss's son next.

Baker also told the dispatcher that he didn't realize his daughter was missing until afterwards because, as he puts it, she rarely comes out of her room.

"My daughter, I think, is coming into puberty... so we only see her when she comes out and wants something."

Police believe that Zahra is dead but have not arrested anyone in her murder.

Authorities say the girl's stepmother, Elisa Baker, admitted to writing the fake ransom note. She has also been charged with obstruction of justice.

The father has not been ruled out as a suspect in the case.

Investigators searching for the missing girl said Tuesday they want medical records from her native Australia, including details on the prosthesis she's had since losing a leg to bone cancer.

Hickory Deputy Chief Maj. Clyde Deal said detectives need to know the model, serial number, and composition of the artificial leg from the Australian medical facility that fitted it for Zahra Clare Baker.

Authorities say she was seen in public as recently as two weeks before she was reported missing.

The Associated Press contributed to this report.