3 Nephi 6:25

therefore a complaint came up unto the land of Zarahemla, to the governor of the land, against these Judges which had condemned the prophets of the land unto death, not according to the law.

So someone made a complaint to the governor of the land in Zarahemla. The complaint was against these judges who had killed the prophets of the land without following the law.

So a complaint was filed in Zarahemla with the governor against the judges who had illegally condemned the prophets to death.