Federal immigration agents in June flagged 59 people at Costa Mesa's city jail as suspected immigration violators — the highest monthly total since checks began seven months ago, according to data from Immigration and Customs Enforcement.

Most of the arrestees flagged in June are Mexican nationals, with three from Honduras and one each from Ecuador and Peru, immigration officials said. Costa Mesa police first arrest or detain people on suspicion of other crimes, and when they get to the jail a federal agent checks their immigration status.

Those suspected of violations could face deportation or wait for court proceedings on the original reason for their arrest. Including those flagged in June, agents have identified 321 people in Costa Mesa's jail that they believe violated immigration laws.