huffingtonpost.com | MEXICO CITY — Scores of police officers – including the entire department of one town – have been detained in Mexican probes of killings and kidnappings.

Mayor Alfredo Osorio of the Gulf coast town Tierra Blanca said Monday that about 90 city policemen were being held for questioning about the kidnapping of undocumented Central American migrants.

The officers – the town's entire local force – were detained by state police and soldiers and taken to the capital of the Gulf coast state of Veracruz for questioning. No formal charges had been filed.

The police allegedly kidnapped the migrants to shake them down for money. Central Americans frequently are robbed or abused by police or by drug gangs as they cross Mexico to seek work in the United States.

In the central State of Mexico, prosecutors announced the arrest of two policemen and two former officers on charges they participated in 11 killings related to robberies.

The officers, ex-officers and a fifth man posing as a police office, had been assigned to two towns on the outskirts of Mexico City. They were detained over the weekend.

Mexico State Attorney General Alberto Baz Baz said the men allegedly preyed on businessmen and professionals, snatching them off the streets to steal debit cards and other possessions, and then often killing them. Another ex-officer is being sought in the case. Some of the crimes were allegedly committed while the officers were on duty.

The suspects face possible prison sentences of up to 70 years. They had no attorney of record