WASHINGTON - The FBI denied Thursday that it ever overestimated the potency of the anthrax spores used in mailings that killed five people in 2001. The bureau also rejected a request for a classified briefing on the case from Rep. Rush Holt, D-N.J. Citing media reports, Holt said Wednesday that the FBI should have determined in days, not years, that the anthrax was less sophisticated than initially believed. Shortly after the attacks, media reports said the spores contained additives and had been subjected to sophisticated milling — both techniques used in anthrax-based weapons — to make them more lethal. Earlier...