I ask those questions too when I go to Venezuela. I think it may be a combination of several things.
One is the transition of the police force, which is perhaps not a good presence in some of the areas, or simply not a presence at all in some of the poorer areas where crime seems to be higher. Another reason might be the displacement of some of the drug violence. Venezuela is not a producer, and as Mexico and Colombia crack down, downstream elements of the drug trade could be moving into Venezuela on the transit side. Still another possibility is that, ironically, as economic growth increases, crime seems to increase. That is counterintuitive, but it's the way it seems to be going. Yet another factor could be the availability of small arms among the population and the consequent use of those arms.