A US judge ruled on Monday in favour of parents who sued conspiracy theorist Alex Jones for saying that the massacre at Sandy Hook Elementary School was a hoax, a lawyer for the families said.
Twenty-six children and teachers were shot dead at the school in Newton, Connecticut in December 2012 by 20-year-old gunman Adam Lanza, who then killed himself.
Jones, a far-right broadcaster who runs the Infowars news service, has claimed the mass shooting was staged as part of a government plot to take away Americans' guns.
He even said that the bereaved families were paid actors.
In 2018, six families of victims filed a lawsuit against him, claiming that he had made millions of dollars from peddling a narrative he knew to be false.
Connecticut judge Barbara Bellis held Jones liable by default after he refused to hand over documents, including financial records, requested by the court, US media reported.
“Mr Jones was given every opportunity to comply but when he chose instead to withhold evidence for more than two years the court was left with no choice but to rule as it did today,” Chris Mattei, who represents the plaintiffs, said in a statement.
“While today's ruling is a legal victory, the battle to shed light on how deeply Mr Jones has harmed these families continues,” he added.
A judge in Texas recently issued similar rulings in three defamation lawsuits brought by Sandy Hook families there.
Juries in both states will now decide how much Jones, who has since acknowledged that the shooting was real, must pay the families.