As a lawyer, he has represented powerful bankers and businessmen accused of fraud.

Javier Lozano, Mexico's labour minister, said: "He's a magnificent lawyer. He's a man with a firm hand ...  the arrival of Fernando Gomez-Mont should fill us with hope."

Bribery and intimidation

Calderon has made winning the so-called "drug war" a cornerstone of his presidency.

Rumours have been rife that Mourino's death was caused by the drug cartels [AFP]

Violence involving the army, federal police and rival gangs has killed more than 4,000 people across Mexico this year.

With mid-term congressional elections due in July 2009, Calderon said he had asked Gomez-Mont to work to keep drug gangs from interfering with elections.

Calderon has warned in the past that drug cartels have tried to intimidate and bribe candidates.

Effectively a vice president, Mexico's interior minister is in charge of domestic security but also works with opposition parties to drive the government's agenda in congress.

As an independent lawyer, Gomez-Mont defended high-profile clients such as ex-president Carlos Salinas, a former director of oil monopoly Pemex, and the Canal 40 television network.