Gunmen were waiting for Mr Millan outside his home, police said
A senior Mexican police official has been gunned down in the capital, Mexico City, officials have said.
Edgar Millan Gomez was in charge of co-ordinating national police operations against drugs traffickers.
He was shot nine times outside his home early on Thursday and died later in hospital, officials said. Two of his bodyguards were wounded in the attack.
Police are investigating if the attack was drug-related. Several top policemen have been killed in the past week.
Police said a group of gunmen had attacked Mr Millan.
"They were hunting him," a spokesman for the security ministry told Reuters news agency.
Police have arrested a 34-year-old man in connection with the attack.
Lucrative trafficking routes
Mexico has seen a surge in drug-related killings recently. Last year, 2,500 people were killed; so far this year, 1,100 people have been killed.
Two other senior police officers were killed in Mexico City in separate incidents last week.
And earlier this week, a senior officer in Ciudad Juarez - across the border from the United States - was ambushed as he left police headquarters.
President Felipe Calderon has sent nearly 30,000 soldiers and federal police to fight Mexico's powerful drug cartels since he took office in 2006.
The drugs cartels have fought back by attacking security forces. They are also fighting with each other to control lucrative trafficking routes.