MEXICO CITY — Who's killing Mexico's journalists?

Reporters and editors have increasingly been targeted for murder during the ongoing war against Mexican drug cartels. But a recent investigation by Mexico City-based newspaper El Universal shows that a majority of the journalists killed were not investigating narcotics trafficking, but local police news and national politics.

Some 58% of the 88 journalists murdered in Mexico since 2000 primarily covered police news and national politics, compared to only 23% covering narcotics trafficking. The report illustrates how reporters in the country have become targets not only for drug cartels, but also for corrupt local governments involved in drug trafficking.

Mexican journalists are often on the front lines of their country's vicious struggle against the cartels, but they also frequently uncover financial and political corruption at all levels of government. Seven reporters have been killed so far in 2015, representing a worrying rise since numbers began to fall after President Enrique Pena Nieto took office in 2013, promising to end his predecessor's full-blown war on the country's numerous drug cartels.

According to the El Universal report, most of the murdered journalists were gunned down in their homes or on the street, and over half of the assassinations occurred in the conflict-ridden states of Veracruz, Tamaulipas, Chihuahua and Guerrero. In areas where drug cartels may hold more power or legitimacy than the government, or where police themselves are linked to organized crime, the lines become dangerously blurred for investigative reporters.

"Some local administrations have been taken over by organized crime," said researcher Luis Daniel Vazquez. "This is very grave, because journalists reporting threats to the police worsen their own situation."

In cities like Veracruz, the constant killings have intimidated newspapers into refraining from exposing too much information on the local drug trade. But in others, like the once-infamous Ciudad Juarez, journalists have continued to risk their lives for their laudable work. Elsewhere the situation is more complicated, and some cartels have even sought to establish relationships with the press to smear and keep tabs on their rivals.