Murders in Rio de Janeiro state are down 7 percent so far this year compared to 2011, as the government continues to roll out a scheme to reclaim favelas from criminal groups, though one study indicates that militias may simply be disappearing their victims.

There were 3,028 murders in Rio between January and September, a 7.6 percent decline from the same period last year, according to the Institute of Public Security (ISP). This continues the year’s record low murder rate, the lowest since the institution began keeping records in 1991, reported R7.

Other types of crime also dropped, including street robbery, which was down 22 percent compared to last year, and vehicle theft, down 5 percent.

InSight Crime Analysis

Part of the drop in homicides is likely connected to Rio de Janeiro’s program to send the security forces to “invade” favelas controlled by drug gangs and militias groups, following up by installing elite pacifying police units, or UPPs. In November 2011, there were some 19 UPPs in place in the city — now there are 28. One recent study found that these units, designed to be a permanent presence in these neighborhoods, saved 60 lives per year per 100,000 inhabitants in the areas where they are stationed.

The UPPs are also meant to build relations with communities, bringing state presence to areas which have long been abandoned by the authorities. There are also signs that the units are fulfilling their mission too — statistics released by the ISP earlier this year showed that the number of killings by police was down over 40 percent in the first six months of 2012 compared to the same period in 2011.

However, it’s also worth bearing in mind the results of a study into militia activity published this month by the Analysis of Violence Laboratory (LAV) of Rio de Janeiro State University. The authors found that in the face of tougher law enforcement, militia groups (which are mostly made up of police), have become more discreet, hiding the corpses of their victims instead of leaving them to be found.