A photojournalist who had received threats over his work in the northern Mexican state of San Luis Potosi has been found dead, the government said Friday, a day after he was kidnapped.

The federal Mechanism to Protect Journalists and Rights Activists called for an "immediate and effective investigation" into the killing of Edgar Daniel Esqueda, who was reportedly kidnapped Thursday by gunmen disguised as police officers.

He is at least the 11th journalist killed so far this year in Mexico, which rights groups say drug wars and corruption have made one of the most dangerous countries in the world for the press.