Holding the city responsible for the actions of Lopez-Sanchez could be difficult, legal experts said. Similar lawsuits alleging that so-called sanctuary city policies contributed to killings by illegal immigrants have failed, including a high-profile case in San Francisco.
Courts previously threw out a wrongful death lawsuit filed against the city for failing to turn over a gang member in the country illegally to federal officials before he gunned down a father and his two sons. A state appeals court said the sanctuary policy was not intended to prevent violent crime.
Attorneys also said cities and counties are legally protected from most lawsuits involving police failures to prevent crime.
"It's difficult," said Matt Davis, an attorney who represented the Bologna family. "Cities aren't required to provide police protection."
The parents said they were filing the legal claims to prevent a similar tragedy.
"We're here not only for Kate, we're here for every citizen of this country who comes to San Francisco," Jim Steinle, the father of the victim, said at a news conference on the steps of City Hall. "If you think this can't happen to you, think again."
Juan Francisco Lopez-Sanchez, 45, has pleaded not guilty to a murder charge in the case. He told police he fired the fatal shot accidentally while examining the ranger's gun after finding it under a bench on Pier 14.
The shooting triggered a national debate over immigration after it was revealed that the Sheriff's Department had released Lopez-Sanchez despite a federal request to detain him for possible deportation. Lopez-Sanchez was previously deported five times to his native Mexico.
Sheriff Ross Mirkarimi said his department was following city law when it released Lopez-Sanchez in April after prosecutors dropped old marijuana possession charges against him.
San Francisco and other cities and counties across the state have enacted policies of ignoring so-called detainer requests from Immigration and Customs Enforcement to hold jail inmates thought to be in the country illegally for deportation proceedings.
The Steinle family claimed the sheriff violated federal laws when he issued a memo in March barring jail staff from communicating with federal immigration officials about detainer requests.
Mirkarimi has said his department requires federal officials to obtain a warrant or some other judicial notice in order for his jail to hold an inmate facing possible deportation.
Sheriff's spokeswoman Kenya Briggs said Mirkarimi can't comment on potential litigation but continues to extend his sympathy to the Steinle family for their loss.
The family also accused ICE, an agency within Homeland Security, of failing to obtain a warrant or judicial notice required by San Francisco to detain and deport Lopez-Sanchez.