Gunmen shot and killed a former police commander and opposition politician in his office in Tijuana on Thursday, officials said.
Lawyer Eleuterio Cachu Ortiz, who was shot three times in the head, was the fourth current or former police official to be killed in the past two days.
"He was in his office when the murderers entered and shot him with a gun," said a spokesman for the Baja California attorney general's office, Jose Manuel Yepiz.
Cachu was the commander of the Federal Judicial Police in the state and a candidate for a seat in parliament for the opposition Democratic Revolution Party in this northwestern border city of 1.3 million inhabitants.
The police chief of Gomez Palacio city in the northern state of Durango was gunned down late Wednesday.
Earlier Thursday, a gang of 40 armed men attacked a police headquarters in San Francisco de los Romo, in the central state of Aguascalientes, killing two police officers.
Some 120 policemen were killed in Mexico last year, according to official figures.
President Felipe Calderon has dispatched some 50,000 soldiers and thousands of police in a nationwide clampdown to confront the country's powerful drug cartels, but has so far failed to stem drug-related violence that has claimed over 14,000 lives in the past three years.