MONTERREY -- Javier Guzman, a 25-year-old industrial engineer, eased his SUV toward the curb on a recent Sunday as a masked state police officer in the middle of the road signaled him to pull over.
Guzman rolled down his window, greeting the officer with a "Buenas tardes."
"Do you live here? Where are you coming from?" the officer asked.
"I live here, this car is mine," Guzman replied. He had nothing to hide, yet began coughing nervously.
The officer, dressed all in black, from combat boots to hooded ski mask, circled the vehicle. A long automatic assault rifle dangled at his side. After a few more questions, he let Guzman drive on.
Such checkpoints are now part of daily life in Monterrey, a metropolitan region of more than 4 million -- Mexico's wealthiest and third-largest city. The brief anxiety that these encounters produce in people is probably the least of residents' worries.
Monterrey, the sleek capital of Nuevo Leon state, is said to be in danger of "falling" to organized crime.
The city is beset by shootouts, armed robberies and "mass panic" incidents over any sign of danger.
More than 400 people have been killed in the state so far this year, compared with 315 in the same period in 2011, one local report said. Extortion by cartels or petty criminals is believed to be widespread. And, according to a leaked U.S. diplomatic cable from 2009, "all of the region's police forces are controlled by organized crime."