There was already a warrant out for a New Bedford man when he was spotted by a narcotics unit late Tuesday night.   25-year-old Derrick Vertentes was picked up at abut 11 p.m. while he was walking in the area of Crapo and Rivet Streets in New Bedford.

Vertentes is accused of robbing Charlie's Convenience Store on Hemlock Street over the weekend with a small folding knife.  Police say he took a wad of cash from the store clerk after both his credit and debit cards were declined when he tried to buy cigarettes.