There's another floater. Four years on, there's another victim face down in the waters of Hurricane Katrina, Dr. Ivor van Heerden.

I don't get to use the word "heroic" very often. Van Heerden is heroic. The Deputy Director of the Louisiana State University Hurricane Center, it was van Heerden who told me, on camera, something so horrible, so frightening, that, if it weren't for his international stature, it would have been hard to believe:

"By midnight on Monday the White House knew. Monday night I was at the state Emergency Operations Center and nobody was aware that the levees had breached. Nobody."

On the night of August 29, 2005, van Heerden was shut in at the state emergency center in Baton Rouge, providing technical advice to the rescue effort. As Hurricane Katrina came ashore, van Heerden and the State Police there were high-fiving it: Katrina missed the city of New Orleans, turning east.

What they did not know was that the levees had cracked. For crucial hours, the White House knew, but withheld the information that the levees of New Orleans had broken and that the city was about to drown. Bush's boys did not notify the State of the flood to come, which would have allowed police to launch an emergency hunt for the thousands who remained stranded.