NBCPhiladelphia.com
Security footage from an earlier robbery in Pennsylvania shows Cox threatening a tanning salon employee at needlepoint.
The man suspected of robbing local businesses at needlepoint is wanted for an attempted heist in Wilmington, Del.
Delaware State Police believe Robert Cox walked into the SuperCuts at the Shops of Graylyn along the 1700 block of Marsh Road on Monday and demanded cash.
Cox, 37, is wanted for thee robberies -- in addition to this latest attempt -- over the past few days in both Pennsylvania and Delaware.
In each case, Cox walks into a business and yields a hypodermic needle, threatening to stick the employee if they don't hand over cash, authorities say. He also tells the victims he's infected with HIV.
"Whether it's a loaded gun or a syringe, both should be taken very seriously," Sgt. Walter Newton said.
While no one was hurt and Cox was unsuccessful in his latest robbery, authorities are afraid he'll become more aggressive.
"Just given his randomness all over the state and in Pennsylvania, it just seems like his aggression is getting more escalated and we don't want it to get to that point," Newton said.
Cox, a known drug user with a criminal history, is believed to be driving a silver 2002 Lexus RX300 with Pennsylvania tag numbers EMD-6030.
Anyone with information is asked to call Delaware State Police at 302.834.2630 or Pennsylvania State Police at 484.840.1000.