The police chief of the Mexican border city of Juarez has resigned after receiving death threats from drugs gangs, officials have said.
Guillermo Prieto resigned just days after hit men alleged to be working for one of the city's drug cartels killed the city's second most senior police officer, Reuters news agency reported.
Authorities say a former official from Mexico's presidential guard Roberto Orduna, will replace Prieto.
At least six top police officers have been killed in Mexico in the past two weeks as Felipe Calderon, the Mexican president, continues his campaign against the country's drugs cartels.
They include Edgar Millan Gomez, the acting head of Mexico's federal police force, who was shot dead in an ambush outside his home in Mexico City in early May.
More than 2,500 people are thought to have died in drug-related violence this year including about 200 alone in Juarez, opposite the US city of El Paso in Texas.
The death toll comes despite the president deploying more than 1,000 troops and heavy weaponry in the city.
Calderon has deployed 25,000 troops and federal police to fight drugs cartels across Mexico since 2007.
The number includes 2,700 troops deployed last week to the coastal state of Sinaloa, home to a group of drug gangs allegedly run by Joaquin "Shorty" Guzman.
Violence has surged in Juarez as the gang and its main rival, the Gulf Cartel, compete for the most lucrative smuggling routes over the US border.