A retired Mexican army officer who led an overhaul of the notoriously corrupt police force of the border city of Tijuana has quit as a state law enforcement official after only three months on the job.

The Baja California Public Safety secretary's office says Julian Leyzaola resigned Friday as deputy secretary.

The 50-year-old official says he has to focus on an urgent matter unrelated to his work. He did not elaborate in his resignation letter.

Leyzaola was Tijuana's top cop until November and worked closely with the Mexican army to arrest drug traffickers. He lost that job when the city's new mayor, Carlos Bustamante, replaced him with his top deputy, Gustavo Huerta.