A police reporter for the daily El Zocalo in Saltillo, the capital of the northern Mexican state of Coahuila, and her 2-year-old son have been missing since last week, representatives of the newspaper told Efe.
Stephania Cardoso disappeared last Friday and her mother notified the Coahuila Attorney General's Office a day later.
The journalist has not been in contact with her mother and she failed to show up for work on Friday.
Cardoso, according to her mother, was last seen Thursday night with her son as they headed to a Freedom of Expression Day event.
The journalist arrived home in the early morning hours of Friday and called co-workers to tell them she was safe.
Relatives, according to Cardoso's mother, went to the house on Friday morning and found it ransacked, with a shattered camera on the floor and the reporter's vehicle missing.
The Coahuila AG's office is investigating the police reporter's disappearance.
The Vienna-based International Press Institute, or IPI, and the World Association of Newspapers and News Publishers, or WAN-IFRA, called on Mexican authorities "to immediately investigate last Friday's mysterious disappearance of a Mexican crime journalist and her two-year-old son."
"We are extremely concerned for the well-being of Stephania Cardoso and her son. While the reason for her disappearance is not yet known, Mexican journalists, particularly those who cover organized crime and police activity, are being targeted because of their work with chilling frequency," IPI deputy director Anthony Mills said.
"Cardoso's disappearance comes less than three weeks after a crime journalist in Sonora, Marco Antonio Avila Garcia, was kidnapped and later found tortured and killed. Five journalists have been murdered in Mexico since April 28, including well-known Proceso investigative reporter Regina Martinez," the IPI said.
Municipal, state and federal authorities should conduct an "extensive investigation" to find Cardoso and her child, the Foundation for Freedom of Expression, or Fundalex, said in a statement.
Cardoso covered the police beat, reporting on accidents, fires, robberies and other crimes, "without covering organized crime, specifically drug trafficking," the Fundalex said.
The police reporter is the 15th journalist to disappear in Mexico since 2000 and the second reporter to go missing in Coahuila, the Fundalex said.
Rafael Ortiz, another reporter for the Zocalo newspaper, disappeared on July 8, 2006, the Fundalex said.
Mexico, where nearly 80 journalists have been murdered since 2000, is considered the world's second most dangerous country for members of the media. EFE