MEXICO CITY  Many of the mug shots of drug traffickers that appear in the Mexican press show surly looking roughnecks glaring menacingly at the camera. An anticorruption investigation unveiled last week in the Mexican capital, however, made it clear that not everybody enmeshed in the narcotics trade looks the part.

There was a gray-haired, grandfatherly type who was pushing 70, as well as an avuncular figure with a neatly coiffed goatee and wire-rimmed spectacles perched upon his nose. Some of the five men who found themselves on the front pages of newspapers on their way to jail, wore suits, which made them look more like bureaucrats than bad guys.

Among the greatest challenges in Mexico’s drug war is the fact that the traffickers fit no type. Their ranks include men and women, the young and the old. And they can work anywhere: in remote drug labs, as part of roving assassination squads, even within the upper reaches of the government.

It has long been known that drug gangs have infiltrated local police forces. Now it is becoming ever more clear that the problem does not stop there. The alarming reality is that many public servants in Mexico are serving both the taxpayers and the traffickers.