A suspect in Friday's terrifying New York subway slashing spree that saw four people randomly stabbed and a fifth sucker punched was caught with a bloodied knife and a victim's backpack, prosecutors say. Joseph Foster, 18, was charged Sunday with first-degree robbery, two counts of second-degree robbery and criminal possession of a weapon over his alleged role in the shocking attacks which left one victim blind in one eye. Surveillance footage shows another victim trying to escape from a train before Foster allegedly dragged him back inside, according to Manhattan Assistant District Attorney Katherine Byrns, who suggested the attacks were part of a gang 'initiation'.