A Billerica man who was caught allegedly skipping out on his fare Monday at a Dorchester MBTA stop had a slew of active arrest warrants, Transit Police said. Police said Thomas Chronowski, 27, “piggybacked” behind a paying customer at the JFK-UMass stop at about 10:45 a.m. He had active warrants for credit card fraud over $250, larceny over $250, receiving stolen property, larceny from a building, identity fraud, forgery of a document, and uttering a false document, police said. He was also charged with heroin possession after police allegedly found an unspecified amount of the drug on his person during the booking process.Travis Andersen can be reached at firstname.lastname@example.org. Follow him on Twitter @TAGlobe.