PHILADELPHIA (CBS) — Ten weeks pregnant, Lindsay O’Brien says she never thought twice about racing out of her Market Frankford El Train car at the 63rd St. Station last Wednesday when an alleged thief tried to steal her purse.

In an exclusive interview with Eyewitness News, the 28-year-old expectant mom from Delaware County says she chased Vaughn Matthews, a career criminal with a dozen arrests going back 19 years, down a stairwell, but when she tried to get her bag from him, he lashed out, breaking her wrist and punching her in the stomach.

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That’s when O’Brien says she drew on her 3.5 years of kick-box training, leveling a kick at the suspect’s shin, shattering it in two places.

Officers say they found Matthews, screaming in pain, lying on the street.

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O’Brien says after being checked out at the hospital, her baby is fine, and she is looking forward to testifying against Matthews when her case comes to court.

She wants to thank Philadelphia detectives, along with uniformed officers, and SEPTA police, who she says were there “within seconds” to help her.

Reported by Walt Hunter, CBS 3

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