A grieving couple in Ohio, a retired preschool teacher in South Korea and a woman who left Japan 62 years ago have one thing in common: They are among a small number of people who have sued North Korea.

Their civil litigation — often over physical mistreatment and abductions at the hands of North Korean authorities — is part of a quiet, yearslong effort by a handful of individuals seeking justice despite the huge challenge of ever collecting money from the isolated nation. Similar suits have been filed against the governments of Iran, Syria and other U.S. adversaries.

These families typically hope the lawsuits will keep their accusations in the public eye and lay the groundwork for criminal prosecutions in international courts, said Gregory S. Gordon, a law professor who has served as a prosecutor or adviser for international criminal cases in Bosnia, Cambodia and Rwanda.