Mexican police officers arrested over murder of federal agents
Ten Mexican police officers have been arrested over the torture and murder of 12 federal agents who were investigating a drugs cartel.
Prosecutors in the western state of Michoacán said the municipal policemen had been detained to "determine their responsibility" for the murders and for allegedly carried out "criminal acts" on behalf of a ruthless drug gang called La Familia Michoacana.
Corruption is rife among Mexico's local police forces and officers have not only protected cartels, but also murdered their rivals.
La Familia, a particularly violent group whose members study a special Bible and claim to be evangelical Christians, had the agents killed apparently in revenge for the arrest of Arnoldo Rueda Medina, one of their leaders.
Around 5,500 troops, federal police and navy personnel are being sent into Michoacán, the home state of President Felipe Calderón.
La Familia is a relatively new cartel which announced itself in 2006 by rolling five severed heads on to a bar's dance floor.
A man claiming to be Servando Gomez, its leader, called a local television station last week and said he was attacking government forces simply to defend his members' families and friends.
Mr Calderón believes that the cartel's recent violence shows it has been damaged by the government's campaign.