Sudhir Singh was arrested from the Ghazipur police station area yesterday, an STF release said here.
A .38 bore English revolver, 16 live cartridges, a fake driving license, seven mobile phones, a car and Rs 2,100 were recovered from his possession, the release said.
Singh has admitted to his role in at least three murders in Gorahpur and Lucknow, the release said, adding that six cases are pending against him.