Rupert said the same chlorine dioxide treatment will be used on the building's heating, ventilation and air conditioning system (HVAC), where spores had been found after the letter was opened in Daschle's office.

CNN: Fumigation largely succeeding in clearing anthrax

Murphy says the original design plans were recently discovered, showing how the property was rigged with 200-kilowatt generators, massive air-intake tunnels and a custom ventilation system to be used in the face of disaster.

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