SEOUL, South Korea — State prosecutors are seeking to arrest a South Korean journalist on charges of violating election laws for reporting an unconfirmed suspicion ahead of December’s presidential vote that the brother of the leading candidate might have been involved in the killing of a relative, the journalist’s lawyers said Sunday.

In the indictment, a copy of which was made available on Sunday, the prosecutors said the journalist, Choo Chin-woo, had written articles and made a podcast that “defamed” and “spread false information” about the brother of the governing party’s candidate, Park Geun-hye, with “an aim of blocking her election.”

Ms. Park won the election by a narrow margin and was inaugurated in February. Her office did not immediately respond to a request for comment.

The previous government also pursued criminal indictments of television producers and bloggers on charges of defaming political figures and disseminating false information — a practice that international human rights groups have denounced for creating a chilling effect among government critics.