The shooting of a young woman in San Francisco by an illegal immigrant who had been deported multiple times has increased the focus on “sanctuary cities” and what they mean to legal residents of the United States. Juan Francisco Lopez-Sanchez allegedly shot 32-year-old Kathryn “Kate” Steinle in the back on July 1. She was walking with her father along San Francisco’s Embarcadero waterfront when she was shot. Lopez-Sanchez has been charged with murder in the case.

People arrested by local law enforcement generally have their fingerprints sent to the FBI to investigate whether they are wanted for crimes in other jurisdictions. Another federal program also forwards those fingerprints to the Department of Homeland Security to check for immigration violations. If immigration violations are found on their record, ICE agents can request that the person be held for up to 48 hours after they have been cleared of local charges. Some authorities in “sanctuary cities” say that the program was being abused by ICE to round up undocumented immigrants with little to no criminal record and that the cost of holding immigrants for ICE was prohibitive.

Federal immigration authorities said that local police ignored a request to hold Lopez-Sanchez, an undocumented Mexican felon, for deportation. San Francisco’s sheriff has publicly defended the release of the Mexican immigrant. The sheriff’s department said that federal authorities failed to provide legal basis to continue holding him prior to his release.

More than 200 cities around the country have passed laws to make them “sanctuary cities” for illegal immigrants. In these cities, law enforcement officers are prohibited from detaining suspects based solely on requests from Immigration and Customs Enforcement agents. Several of these cities have announced that they would be examining their policies in the wake of the July 1 shooting. While the outcry has been vocal, none of the “sanctuary cities” are saying that they will change their immigrant detention polices.