The abduction and murder of two-year-old James Bulger in the UK

The case of the abduction and murder of two-year-old James Bulger in the UK had such profound and farreaching impacts on British criminal law, justice, public attitudes to children, and the organization of family life. What criminal cases in the U.S. can you think of that have had a similarly seismic impact on aspects of legal, social, and cultural experience?