A police officer who used a Taser on a nine-year-old girl-- that's the issue for South Tucson police tonight.

Investigators are looking into whether the officer did the right thing- and not because of the girl's age.

The electrical jolt from a Taser can drop a strong man in his tracks. Police are using the stun guns more and more as a way to defuse dangerous people without killing them.

But on May 8th, South Tucson police answered a call to Arizona's Children Association and used a Taser ...on a nine year old girl.

There's an investigation not simply because police Tasered a child but because she was already in a police car and already handcuffed at the time that they did it."

South Tucson Police have a six page policy on how police should use force. More than half of it describes how and when to use Tasers.

The policy says officers may not use a Taser when someone is cuffed unless they are still violent and uncontrollable.

South Tucson's police chief says he can't say more about how the child behaved until the investigation's complete.

Privacy law prevents the president of the Children Association from even confirming the girl was there.

Frederick Chaffee does say the home takes in children who might otherwise be in a psychiatric hospital. He says workers usually try gentle guidance, but...."There have been occasions where a youngster has gotten very very violent and very aggressive and we need to bring police in to help us with that."

Rather than investigate one of their own, South Tucson police asked Pima County Sheriff's Deputies to look into the incident. Deputies may finish their work by the end of the week.