A new study indicates four out of five homicides go unpunished in Mexico, in part because authorities focus on easier, less serious cases.

The study says 96.4 percent of murders in northern Chihuahua state don't result in prison sentences.

The group Mexico Evalua released the nationwide figures in a report Monday.

Police in one Chihuahua city made headlines in December for ticketing a 6-year-old for reckless driving, driving without a license and not registering his miniature gasoline-powered motorbike.

In northern Nuevo Leon state the murder rate soared by 617 percent between 2009 and 2011, but prosecutors there are going after a pair of chefs for allegedly stealing recipes.