Guardsmark, the private security service firm, expanded its presence at 10 Rockefeller Plaza by leasing the entire 12th floor for the next seven years. The deal was structured so that the firm renewed its current lease of 6,725 square feet and will also take immediately possession of additional 6,714 square feet. Guardsmark will take possession of the remaining 2,534 square feet in October 2003. Nick Gilman, Gordon Ogden and Graham Alton of Byrnam Wood represented Guardsmark. Ed Gargiulo and Simon Wasserberger of Tishman Speyer represented the landlord, RCPI Properties.