PIEDRAS NEGRAS, Mexico (AP) - A police beat reporter at a newspaper in northern Mexico and her infant son are missing and they are feared kidnapped, a newspaper official said Tuesday.

Reporter Stephania Cardoso works for the El Zocalo newspaper in the city of Saltillo, about 200 miles (320 kilometers) from the U.S. border. She has been missing since Friday, said Eduardo Mendoza, El Zocalo's editor.

She was last seen at a party with colleagues Thursday night. Mendoza said she called a colleague after arriving home at around 2 a.m.

The reporter's mother, Sylvia Cardoso, told Mendoza that she fears that her daughter was kidnapped and that the house had been ransacked.

State and federal prosecutors said they are investigating the case.

Cardoso is the 16th journalist in the country to be disappeared, according to the Mexican Human Rights Commission.

The Miami-based Inter American Press Association in a statement denounced Cardoso's absence and urged Mexican authorities to find her quickly.

"We are at an unusual instance where not only the journalist has disappeared, but also her son," said the president of the group's committee on press freedom, Gustavo Mohme.

The Zetas drug cartel kidnapped and killed Zocalo reporter Valentin Valdes Espinosa in January 2010.