Who is to blame? It goes without saying that the criminals are responsible (and The Guardian is happy to leave that unsaid) but a number of institutional factors help. The paper suggests:

Reason A:

Article 701 of the Louisiana code of criminal procedure, which states that suspects cannot be held for longer than 60 days on felony arrest without an indictment.
..
Whatever the reason, 701-related laxity has become so common that New Orleans street hustlers have dubbed doing 60 days in jail for a killing a "misdemeanour murder." This was no exaggeration: in addition to the thousands of suspects being released under Article 701, the Orleans Parish district attorney's office secured just one conviction in the 162 murders committed in 2006.

Incredibly, the killing fields of New Orleans do not appear to rank high as a concern among state and local officials. The mayor, Ray Nagin, has been silent in the face of the sort of mass killing that occurred and often dismissive of it. This summer, he told a group of reporters that the murder rate "keeps the New Orleans brand out there."

Perhaps the most serious blow to New Orleans' ailing criminal justice system is the recent election of former Republican Congressman Bobby Jindal as Lousiana's governor. Mr Jindal has boasted that he will turn New Orleans-which is already profoundly suffering from a lack of public resources-into a model of far right privatisation politics on such issues as education and healthcare.

Allow me to pontificate for the paper. Maybe criminals have been murdering people in anticipation of school prvitization? Maybe drug dealers are shooting each other to save up money for their Aunt's hip surgery? Or just maybe the author has it in for Republicans in general.