Might you be referring to these pictures?
After Katrina there were emails circulating that stated that the crocodilian seen above was an Alligator, and that it had eaten the dead left laying on the screen
The truth is that the creature in the picture is not an alligator. It is a Nile crocodile, the second largest crocodilian in the world (the largest is the Australian Salt-water crocodile). The Nile crocodile is found throughout most of Africa, and it is a veritable man-killer and man-eater. And they can grow to prodigious lengths ....the crocodile in the picture is 16 feet long (the email said that the 'alligator' was 21-22 feet long ....it is neither an alligator, nor is it 21-22 ft long), but Nile crocs have been known to get up to 20 feet and maybe more than that. I once saw a Nile crocodile nab a Wildebeest, and I tell you this ....that thing was a monster. The head alone seemed the size of the Wildebeest (which is roughly the size of a cow).
This crocodile (the one in the pic that emails claimed was an 'alligator') was killed in the Republic of the Congo. Alligators never get close to crocodile sizes, and this beast was thousands of miles away from New Orleans.
I'm not sure whether that is the email you are talking about, but the fact that it mentioned a '22 foot long alligator' makes it seem as if it is the same one (and gators do not even get that large ....the only crocodilians that can get that big are the Salt-water croc from Australia, the Nile croc from Africa, and maybe in a blue-moon the Mugger croc from India. All are killers, all are huge, neither is an alligator).