Republican lawmakers confronted the Democratic mayors of four “sanctuary cities” over immigration policies that they believe have shielded criminal immigrants in the United States illegally, placing Americans and federal officers at risk.

Here's a rundown of several key claims made during the hearing, and our reporting on the issues and numbers referenced by officials.

Rep. Paul Gosar clashed over immigration with big city Democratic mayors in a congressional hearing, going as far as to quiz them on Arizona’s controversial Senate Bill 1070 law. The House Committee on Oversight and Government Reform hearing,

She stood up for the city and refused to cower in the face of threats and smears,” one of more than 1,700 respondents said. The post Mayor Michelle Wu represented Boston well at the ‘sanctuary cities’ congressional hearing,

Fla., said she is referring the Democrat sanctuary city mayors who testified before Congress to the Justice Department for criminal prosecution.

Sanctuary laws are in place in several US cities. The mayors of four of the largest ones defended laws that require them to provide care.