South Korean prosecutors are seeking a 12-year jail sentence for Samsung Electronics vice-chairman Lee Jae-yong.
Mr Lee is facing charges over his alleged role in a bribery scandal which led to the ousting of the ex-President Park Guen-hye.
It is alleged he made a large donation in exchange for government support of a merger of two Samsung subsidiaries.
He has been in prison since February over the scandal, but denies any wrongdoing.
At the final hearing, prosecutors called Mr Lee the “ultimate beneficiary” of crimes committed in the scandal.