A Dorchester man pleaded guilty to manslaughter charges on Thursday for the fatal stabbing of another man following a 2010 fight at a Roxbury liquor store, a spokesman for Suffolk District Attorney Daniel F. Conley said. Tajuan Holloman, 42, admitted he stabbed Thomas Whitley, 30, a father of four, outside Dearborn Liquor Store on Nov. 6, 2010, Conley’s spokesman said in a statement. The spokesman said Holloman was identified based on surveillance images and witness statements and admitted in December 2010 that he had fought Whitley over an unpaid drug debt. A Suffolk Superior Court judge sentenced Holloman to 12 to 13 years in prison.Jeremy C. Fox can be reached at firstname.lastname@example.org. Follow him on Twitter @jeremycfox.