Madison Police say a bank security guard shot a robber to death at a Chase Bank location Thursday afternoon.  The suspect entered the bank with his face covered at about 4:50 P-M, handing a bag to a clerk and demanding money.  The security guard says the man was posturing as if he had a gun, so he shot him.  Paramedics weren’t able to stabilize the wounded robber for transport, he died at the scene.  Seven other people in the bank at the time were not injured.  The dead man is believed to be Latino and in his 20’s.  Police haven’t confirmed if he had a weapon, or not.  This was the fourth robbery at that branch bank in the last 14 months.