In the three months since the force started, it has handled 3,100 reports, made 123 arrests and issued 53 summonses

His mansion had been burgled, masked gunmen had robbed the bar next door and the French Quarter of New Orleans was suffering a crime wave.

Sidney Torres IV decided to tackle the problem. With the aid of the city government, Mr Torres, a multimillionaire, set up a police force. He hired off-duty police officers and supplied electric carts. He built a smartphone app that would let residents instantly report and post pictures of crimes, summoning officers to the scene in minutes.

Mr Torres, who made his fortune in the rubbish disposal industry, is now credited with cleaning up crime. The Times-Picayune reported that in the three months since the force started, it had handled 3,100 reports, made 123 arrests and issued 53 summonses. Its response