this is 31-year-old gavin mack a woman using this knife and then use the credit card he had just stolen from her at a local store. police say it started here tuesday afternoon when he approached the 74-year-old woman as she put groceries into her car. >> he demanded the money while displaying a large six to eight inch military style knife. she immediately started to scream for help and when she did the suspect pushed her to the ground and a small struggle ensued where he stole her wallet from her purse. >> police say that well he spoke to the woman and other customers, the victim got word one of her credit cards had been used in a local kmart. shows him entering the store. >> we went there and obtain video surveillance from the store and learned the system -- suspect had used a credit card to obtain $500 worth of gift cards from the start. the lookout for a light blue honda acura with a new hampshire plate. mac was stopped by state police -- state police about an hour after the 74-year-old initially reported the robbery. >> he was cooperative and through the course of the investigation