Mexico City is one of the safer cities in a country fighting a long-term drugs war, and it is hoped that a new smart phone application allowing people to direct police to crime scenes will make it safer still.
Free and popular, it is the 10th most uploaded application in a country where, according to a national watchdog organisation, less than three percent of the population trusts the police.
Some people have criticised the government, saying that only people who can afford smart phones will have access to the service.
Al Jazeera's Rachel Levin reports from Mexico City.