The acting chief of Mexico's federal police was shot to death early Thursday outside his home in the capital.
The Public Safety Department said Edgar Millan Gomez was shot 10 times and died hours later in a hospital. Two of his bodyguards were wounded.
A police official, who was not authorized to give his name, said Millan had been temporarily heading the federal police since his superior was promoted to a deputy Cabinet position on March 1.
Police arrested a suspect with a record of car theft but have not yet determined a motive for the predawn attack. The official said police were investigating possible drug links.
Mexico has suffered a wave of organized crime and drug-related violence in which more than 2,500 people died last year alone.
Millan was in charge of coordinating drug operations with the military. Since taking office in 2006, President Felipe Calderon has sent more than 24,000 troops to drug hotspots. Cartels have lashed back, killing soldiers and federal police.
Millan was the second top federal police official killed in less than a week in Mexico City. A Mexican federal police intelligence analyst was killed on May 2 in an apparent armed robbery attempt outside his home.
In January, police in Mexico City arrested three men armed with assault rifles and grenade launchers who were allegedly planning to assassinate Jose Luis Santiago Vasconcelos, a top prosecutor who oversees the extradition of drug traffickers.
Calderon condemned the attack on Millan.
"The government of Mexico expresses its deepest sympathy in light of this cowardly killing of an exemplary official, committed to the safety of Mexican families," Calderon's office said in a statement.
Millan helped capture one of Mexico's most feared kidnappers, Andres Caletri, in 2000, and helped disband two notorious abduction rings. In 2001, he was named head of anti-kidnapping operations for the Federal Agency of Investigation, Mexico's version of the FBI.