3 Nephi 7:1

Now behold, I will shew unto you that they did not establish a king over the land; but in this same year, yea, the thirtieth year, they did destroy upon the judgement seat, yea, did murder the Chief Judge of the land.

They did not choose a king to rule over the land. But in the thirtieth year, they killed the Chief Judge of the land.

They never did appoint a new king. Instead, in that same year—the thirtieth year—they murdered the chief judge who sat on the judgment seat.