The parents of Kathryn Steinle, who was allegedly shot and killed by a Mexican national, on Monday said that they supported a law that would require prison time for individuals who illegally return to the country.

The legislation proposed by conservative commentator Bill O'Reilly would create a mandatory five-year federal prison sentence for those who are deported after committing a crime, then re-enter the country illegally, Fox News detailed.

Pleasanton, California, residents Jim Steinle and Liz Sullivan told the host that they wanted to keep other families from what they went through due to the violent death of Kathryn Steinle, their 32-year-old daughter, the Los Angeles Times reported.

"We feel the federal, state and cities -- their laws are here to protect us, but we feel that this particular set of circumstances and the people involved, the different agencies let us down," Jim Steinle said. "You want to make it so much better for everybody in the United States that this, as you say, would never happen again."

Kathryn Steinle had been walking along a waterfront in San Francisco when she was shot by a gun allegedly fired by Juan Francisco Lopez-Sanchez, a man believed to be in the country illegally, The Associated Press recalled. The Mexican national, who had been released from jail months before the shooting, has pleaded not guilty, the newswire noted.

The young woman's death, meanwhile, has led to a national debate on so-called "sanctuary cities," which do not allow municipal funds or resources to be used to enforce federal immigration laws. Some 200 jurisdictions across the United States follow that policy, according to the Daily Signal, and O'Reilly and other conservative commentators have strongly criticized their approach, the AP noted.

Several Republican presidential candidates, including former Florida Gov. Jeb Bush, Florida Sen. Marco Rubio and Kentucky Sen. Rand Paul, have also said that the practice must be reconsidered.

"We ought to eliminate sanctuary cities," Bush told Politico, adding that the federal government "should not provide law enforcement monies for cities like San Francisco until they change their policies."

Democratic frontrunner Hillary Clinton, on the other hand, continues to support sanctuary cities, according to the Washington publication.