The ruling leaves in place an appeals court order requiring a South Carolina department to hand over records that Google says it needs for its legal defense.
The extension was announced by the election commission after a judge granted an extension in response to a lawsuit filed by the South Carolina Democratic Party.
Murdaugh had been sentenced to 40 years in prison for financial crimes, while simultaneously serving life in prison for the murders of his wife and son.
South Carolina has become the fourth state to have to disclose its voter registration list to the watchdog Public Interest Legal Foundation for analysis.