A Justice Department inquiry into Transportation Secretary Federico Pena's dealings with his former firm turned up no credible evidence that he broke federal laws, Attorney General Janet Reno announced today. Prosecutors had been investigating Pena's role in awarding a Los Angeles transit system contract to his former management company. The independent counsel law, which gives the Justice Department 30 days to conduct such an inquiry, gave Reno until Friday to determine whether to seek an outside attorney to investigate Pena; today's ruling means she will not. On Tuesday, she sought an independent counsel to determine whether Housing Secretary Henry Cisneros broke the law by misleading the FBI about how much money he had paid an ex-mistress. The Justice Department also is in the process of deciding whether to hire an independent council to investigate Commerce Secretary Ron Brown.