When times are bad, conventional wisdom says, crime goes up. The idea is that desperate times can drive even law-abiding citizens to desperate crime.

Not this time. During the worst economic downturn most people can remember, the number of crimes reported in Ann Arbor fell last year.

But don’t expect to see Ann Arbor police chief Barnett Jones celebrating. “I’m happy to say, yes, in some categories, crime is down,” Jones says–then quickly adds, “but it’s also gone up in some others, so don’t get any sense of false hope.”

Jones won’t share Ann Arbor’s official crime stats until the FBI certifies them later this month, but a comparison of the crimes reported on the Observer’s monthly Crime Maps for 2009 and 2010 paints the big picture. In the five categories tracked, crime reports to the Ann Arbor Police Department and the U-M Department of Public Safety fell slightly, from 828 to 790. The biggest drop was in burglaries, down from 576 to 524. Sexual assaults scarcely changed, going from fifty-nine to fifty-seven, as did vehicle thefts, up just one, to 130. The one category showing a significant rise is robberies, up by fifteen, to seventy-nine. Homicides, thankfully, remained flat at zero.

Jones explains the drop in burglaries by saying “the community has done their part. We asked them to lock their doors and windows, and people have started doing it.” Not all of them, though. “I still meet people who say ‘I’ve been here nineteen years and I haven’t locked my doors yet,'” says Jones in exasperation. “I say to them, ‘We’re in Michigan in the worst economy since the Depression, and we’ve got people out there who’ll steal your $800 flat screen TV. You’ve got to lock your doors!'”

Though he won’t give the still- unofficial totals for crimes the Observer doesn’t track, Jones will talk about the trends. Assaults–basically people getting into fights–“are down, because Ann Arbor people are being nicer to each other,” the chief says. “Larcenies were up by two incidents, retail fraud or shoplifting included–which is good: with the economy here in Michigan, I thought they’d run through the roof!”

Jones acknowledges that the lower local crime rate is part of a larger national trend. And so, he stresses, is the movement to shrink police forces. “We’ve got 2,500 less police officers in this state right now,” says Jones, “and in lots of jurisdictions, crime is down because there’re less police officers to do the job. Crime can go down to zero if you don’t have any cops [to take reports].”

The AAPD has shrunk by more than a third over the past decade. “There were 216 sworn offices in 2000,” says Jones. “There’re 124 now, including me. We need more cops!” But, needed or not, they won’t be forthcoming: the 2012 budget proposed by outgoing city administrator Roger Fraser calls for reducing the police force by another thirteen officers.

For the first time, the proposed budget would also tie staff levels to benefit costs–with bigger cuts in the AAPD and other departments where workers pay less toward their health insurance. But the police officers’ union seems determined to hold its ground. Last year’s negotiations deadlocked, sending the contract to binding arbitration that has yet to be resolved.