But teasing the facts out of a flood of rumor and grains of truth will be daunting. It is a "morally treacherous" gambit to measure the actions of stressed people in the virtually lawless state of post-Katrina New Orleans by typical standards, says Peter Scharf, a criminologist at Tulane University. The outcome, he worries, could impact the willingness of first responders – police, doctors and nurses – to stay behind during a major natural emergency for fear of later repercussions.
The United States District Attorney and the FBI are "entering this incredibly gray, confusing period," says Mr. Scharf. "It's like investigating the Battle of the Bulge where everyone is lost in middle of the Ardennes Forest. There's ambiguity in the fog of war."
The New Orleans coroner's office has counted 23 dead with gunshot wounds to their heads, he says. What happened to these people is a mystery to authorities, he adds.
One focus of the investigations is Algiers Point, a historically white enclave on the West Bank of the Mississippi River. As New Orleans flooded, survivors from the Lower Ninth Ward came across on boats, and residents armed up, even walling off neighborhoods.
What happened next, Mr. Thompson alleges, amounted to mob justice. "[V]igilantes and residents – citing the exact locations and types of weapons used – detail a string of violent incidents in which at least eight other people were shot, bringing the total number of shooting victims to at least 11, some of whom may have died," he writes.