Recife is an extreme case. It has a frightening crime problem as these links (1), (2), (3) show.
Extreme cases are interesting from a researcher's point of view as it allows the mental testing of hypothesis. In this case my model of fear of crime. I have shared it before but I do so again.
People base their fear of crime on their perception of crime. They apply that perception to their personal circumstances and take action to avoid or prevent that crime happening to them and who they care for. Now in Recife, interestingly even though the fear of crime is very high, wealthy people still want to live there and visit there on their holidays. Crime avoidance becomes lifestyle changing, only going to certain places at certain times in certain ways. And importantly because it becomes observable in the urban morphology is the trend that those who can afford it live their lives behind walls and security systems. The downside is that by making the private spaces safer the public spaces become more dangerous because the natural defences supplied by communal mutual security (people looking out for each other) is eroded. It is the role of the police to make law-abiding citizens feel safe on their streets so they do not have to hide.
I am always on the look out for proxy measures for confidence in the police. Urban defensive design had already occurred to me but perhaps I should add a street based cafe culture which really should exist in Recife but appears not to, to my list.