MEXICO CITY (Reuters) - Mexican authorities said on Monday they are investigating whether police in the western state of Jalisco participated in the disappearance of three Italian citizens there.

The Naples natives reportedly went missing on Jan. 31 after being detained by police at a gasoline station in the municipality of Tecalitlan in southern Jalisco.

State authorities are “evaluating, using available information” whether police were involved in the disappearance, said Jalisco general secretary Roberto Lopez.

He said state authorities will collaborate in the investigation with Mexico’s attorney general’s office and foreign ministry and the Italian Embassy in Mexico.

Lopez did not say if they were in direct contact with the relatives of the disappeared Italians.

Over the weekend family members and friends took to the streets of Naples to demand that Mexico’s government locate Raffaele Russo, Antonio Russo and Vincenzo Cimmino.

Mexico is facing its worst-ever surge in violent crime, with more than 25,000 killings in 2017, as rival drug gangs splinter into smaller groups and dispute territory.

In Mexico’s most violent states, corrupt cops often collude with criminal gangs.

The Jalisco New Generation Cartel, regarded by the United States as one of Mexico’s most powerful drug gangs, operates in Jalisco.