Two senior Mexican anti-drugs officials have been killed in separate shootings by suspected drug traffickers.
Lugo was shot at point blank range while driving his car
Federal prosecutor Jose Nemesio Lugo was gunned down in his car on the outskirts of the capital, Mexico City.
Hours later Jorge Altriste, one of the highest-ranking police officers in the border city of Tijuana, a drugs hotspot, was also shot and killed.
Almost 800 people are thought to have been killed in Mexico in drug-related violence so far this year.
Jose Nemesio Lugo, 55, investigated drug issues and organised crime in the office of Mexico's attorney-general, and headed a key department.
He was attacked, reportedly by up to three unknown gunmen, as he drove to work in the town of Coyoacan, in a southern area of Mexico City.
Mr Lugo's car was blocked by another vehicle before its occupants ambushed him and shot him dead, the Efe news agency reported.
Apart from drug issues and organised crime, Mr Lugo dealt with migrant smuggling and immigration issues, and had recently been appointed to head a major intelligence unit.
Mr Altriste worked as head of operations for Mexico's elite police force in Tijuana, close to the border with the US.
He was discovered in a crime-ridden neighbourhood of the city with three gunshot wounds to the head, the attorney-general's office told the Reuters news agency.
There were also some signs he had been tortured, Reuters reported.
Tijuana is a major transit point for drugs heading into the US and has become and increasingly violent battleground for the competing drug cartels.
Feuding drug cartels are blamed for many of the deaths in Mexico, which have continued despite a military offensive launched by President Felipe Calderon.
The cartels have been blamed for a series of brutal killings, with many bodies found showing evidence of torture or wrapped in plastic.
In January, Mexico's new President Felipe Calderon sent more than 3,000 soldiers to the northern border city of Tijuana to help fight drug trafficking and gang violence. More than 300 people were killed there in 2006.
This came a month after he dispatched 7,000 troops to Michoacan state on the Pacific coast, where more than 500 people died last year.