More than 4,000 people have died in drug-related violence this year
The ex-head of Mexico's anti-organised crime agency has been arrested as part of a probe into links to drug cartels.
Noe Ramirez Mandujano was held in an operation that has detained other senior officials.
The attorney general said Mr Ramirez accepted $450,000 (£304,000) from cartels and was offered a monthly fee for information.
Mexico's drugs crackdown this year has seen many arrests but thousands have also died in drugs-related violence.
The office of Attorney General Eduardo Medina Mora said Mr Ramirez had spoken to investigators voluntarily and was subsequently detained.
He took up his post as head of the Special Organised Crime Investigation Division in 2006 and resigned in July as part of a shake-up by President Felipe Calderon.
Mr Ramirez is the highest-ranking law official yet detained in Operation Clean-up, which was launched to try to curb corruption linked to drug smuggling.
Five senior officials and two federal agents have been held in the campaign. The arrests include the head of Mexico's Interpol office. Dozens of officials have been sacked.
On a visit to Chile on Friday, President Calderon said: "The Mexican government is firmly committed to the fight against organised crime and not just organised crime but corruption."
Mexican authorities have had success in arresting key members of drug cartels in recent months.
However across the country this year, more than 4,000 people have died in drug-related violence as gangs fight each other and the security forces.
The attorney general's office has particularly targeted links to the cartels of the Beltran Leyva brothers, who recently split from the Sinaloa organisation.