The complicated relationship between crime and the economy

As I've mentioned before, the correlation between crime and bad economic times isn't so simple. Yes, there are many kinds of crime that tend to go up when the economy goes down, but even for those, there are a lot of counter-examples.

Today there's this: the FBI says violent crime was lower in 2008 than in 2007. The NYT summarizes:

In each of the four violent crime offenses, the 2008 rates were down from 2007. Murder and nonnegligent manslaughter dropped 3.9 percent; aggravated assault declined 2.5 percent; forcible rape declined 1.6 percent; and robbery was down 0.7 percent. The figures are based on offenses per 100,000 people.