The senseless murder of a California woman is once again shining a light on the nation's so-called "sanctuary cities," where authorities are not cracking down against those who are in the United States illegally.

Kate Steinle was shot to death last week while walking with her father and a friend at San Francisco's Pier 14. 

The man charged with the murder, 45-year-old Francisco Sanchez, had been deported five times. Most recently he was in jail on April 15, but officials declined to prosecute him and set him free.

Federal officials have criticized the city for failing to notify ICE about Sanchez's release.

San Francisco is one of more than 200 cities that operate with "sanctuary" policies for illegal immigrants. Fox News legal analyst Peter Johnson Jr. explained on "Fox and Friends" where sanctuary cities are located and what policies they have implemented. 

Other major cities operating with sanctuary policies include New York, Miami, Houston, Boston, Chicago and Washington, D.C. 


Johnson Jr. explained that sanctuary policies prohibit local authorities from using city resources to enforce federal immigration laws.

Some states allow illegal immigrants to be released from custody after posting bail or serving time for minor offenses. But often, like in the case of Sanchez, federal authorities are not notified.

The policies began in the 1980s when churches started to provide "sanctuary" to people fleeing violence in Central America. Johnson said it "morphed" to cities across the country. 

ICE released more than 30,500 criminal aliens into the United States in 2014. 

In terms of the 2016 presidential race, Johnson said all of the Democratic candidates support sanctuary policies, while all of the GOP hopefuls are opposed.

Watch the full segment above as Johnson goes over some of the victims of these sanctuary policies.