BRADENTON (CBSMiami/AP) — An internal investigation is underway into why deputies used a Taser three times on a 70-year-old woman after she tried to stop them from coming into her home on her birthday.

The Manatee County Sheriff’s Office will look into whether the agency’s protocol was followed, officials said.

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The deputies went to Barbara Pinkney’s home Thursday, on her 70th birthday, with an arrest warrant for her grandson, who was wanted on a charge of violating his probation. When Pinkney repeatedly refused to let them inside, Deputy Jason Riley tried to enter the home as she tried to shut the door on him.

Riley grabbed Pinkney by the wrist with the intent of arresting her for obstruction when she pushed him in the chest, an arrest warrant said.

Riley then used the stun gun on the woman and when it seemed to have no effect, the arrest report said.

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“He pushed me on the floor and he stunned me again twice on my back,” Pinkey

Pinkney was charged with battery on a law enforcement officer and obstruction. Riley has been placed on administrative leave pending the outcome of the investigation.

Pinkney’s grandson, the whole reason the sheriff’s deputies were there in the first place, has not yet been arrested. It’s not clear if he was even home at the time.

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