Charles Ellicott Commentary Esther 2:6

"who had been carried away from Jerusalem with the captives that had been carried away with Jeconiah king of Judah, whom Nebuchadnezzar the king of Babylon had carried away." — Esther 2:6 (ASV)

Who had been ... —The antecedent is obviously Kish, though as far as the mere grammar goes it might have been Mordecai.

Jeconiah. —That is, Jehoiachin. (See 2 Kings 24:12–16.)

Nebuchadnezzar ... had carried away. —This was in 598 B.C., 117 years before this time, so that the four generations are readily accounted for.