A police dashboard camera shows exactly what happened between a deputy constable and a 72-year-old woman in Austin, Texas right before the officer tased her.

The officer says Kathryn Winkfein -- a great-grandmother -- mouthed off and got physical during a traffic stop on May 11, 2009.

Deputy Chris Bieze stopped Winkfein for speeding. After he completed the paper work -- she refused to sign it. That's when things got ugly. According to the deputy, he shoved Winkfein so she would get away from the side of the highway.

The elderly woman started to tease the officer... "daring" him to use his taser on her. He warned her several times she was in danger of being tasered.

The officer eventually did use the device that delivers a shock. Winkfein wasn't hurt, but you can hear here moans of agony on the tape right after it happened.

Travis County, Texas Sergeant Major Gary Griffin says after reviewing the footage the officer followed policy and stands by his decision to use it.

The dash cam video of this incident lasts about 1:45.