In September, officials removed all weapons from the police force in the Mexican town of Acapulco.

Infiltrate to top police officials are accused of murder, and the entire force is under investigation.

Authorities say drug criminals infiltrated the police force in order to control them.

To infiltrate is to enter or join a group or organization secretly to get information or to harm.

It also means to pass through something.

For example, water can easily infiltrate the soil like us on Facebook at V Away Learning English.