In June 2012, Stockton, California, became the largest U.S. municipality ever to declare bankruptcy. How did it get there? Alison Vekshin, James Nash and Rodney Yap help explain it with the story of how four successive Stockton police chiefs retired after less than three years on the job. (In one case, after just eight months.) With pensions based largely on their final years' salaries, two ended up getting more than $200,000 a year. Deals such as those, which Bloomberg uncovered with the help of Calpers pension data for 521,293 employees, have come back to haunt cities as higher retiree costs combine with growing unemployment and declining property- and sales-tax revenue to deepen financial distress.