Police authorities in North Carolina are apprehensive that Zahra Baker, a 10-year old physically challenged Australian girl who has been missing for over a month, could have become the victim of some foul play after finding new evidence while searching an area called Gunpowder Creek.

Hickory Police Department didn't say what the search teams have found, so as not to endanger the future prosecution of the case, but deputy chief Clyde Deal said the new evidence could throw some light on Zahra's case.

Deal said the new evidence, found November 10, has been sent to North Carolina State Bureau of Investigations lab for analysis and they will receive a report soon.

On October 27, the police authorities found a prosthetic limb in the bush several miles away from where her family once lived. Later they confirmed that the serial number on the limb matched with the one Zahra was fitted with in Australia. Zahra is a bone cancer survivor but a part of her left leg had to be amputated. She also uses hearing aids.

On November 3, the police found a bone in the same area and have sent it to the laboratory for tests.

Deal said police again searched the area where they found the prosthetic limb based on some other information on Thursday morning.

The police force, he said, will not stop searching till they find more clues. Roughly 40 people, both police and civilians, are trying to find Zahra.

It was not immediately known whether Zahra's step-mother is being suspected for foul play.

Hours before Zahra was reported missing to the police, her American stepmother Elisa Baker had written a bogus $1 million ransom note. She was indicted by a grand jury on Monday on a felony charge of obstruction of justice and is in jail.

Zahra's Australian father Adam Baker, who came to know Elisa through a social networking site suspects that she has something to do with Zahra's disappearance.

Zahra was reported missing by her father on October 9 but police suspect she was missing longer than that.

The police have also not also ruled out Zahra's father as a suspect. Adam was arrested this week on unrelated charges of assault and writing false checks and is currently out on bail.

In a letter sent to crime memorabilia dealer Eric Gein, Elisa claims Adam knows where Zahra is and though they really didn't kill her, but what he did after the fact is kinda horrifying.

[Adam Baker] knows what happened to Zahra, and yet I'm the one in here at least for now, she wrote.

Zahra had moved with her father from Townsville in north Queensland to North Carolina and was being home-schooled. Her biological mother Emily Dietrich has not seen Zahra since she was eight months old. Emily, who suffered post natal depression after the birth of Zahra and handed her custody to Adam, arrived in Catawba County on Thursday morning to help the police locate Zahra.