Security footage shows the 51-year-old victim being pulled down a stairwell at the 1500 Market Street SEPTA platform around 5 a.m. on Nov. 9, authorities said.
Police say the robber also took the victim's cell phone and money. He is described as a black man in dark clothes with a full beard and a blue knit cap.
Anyone with information is asked to call PPD at 215-686-8477 to submit an anonymous tip online.
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