The defense reiterated his denial of wrongdoing, questioning whether the prosecution was relying on public sentiment to secure a prison term for Lee, 49, whose father, the group patriarch Lee Kun-hee, was hospitalized in 2014.
The court is due to rule on Lee's case on August 25.
Moreover, Lee has been kept well away from other inmates at the Seoul Detention Centre.
"I have never asked anyone, including the president, for anything for the company or my personal gain", said Lee in a final statement, his voice wavering.
In his remarks wrapping up the trial, Special Prosecutor Park Young Soo said Samsung's alleged bribery was typical of the corrupt and cozy ties between the South Korea's government and big businesses.
Such dealings once helped fuel the country's rapid industrialization but now increasingly are being scrutinized as illegal and unfair.
Park also accused Samsung officials of lying in their testimonies to protect Lee.
Park was removed from office in March and is being tried separately.
Samsung's lawyers do not contest having donated a large sum of money to entities controlled by Choi.
He said he is to blame for the controversy but denied bribing Park and Choi to lean on the national pension fund, which held the controlling vote in the publicly traded company at the time, to back the merger.
Other charges he faces include wrongfully transferring assets overseas and hiding the proceeds of a crime. Now prosecutors are calling for a 12-year jail sentence for Lee, charged with bribery and embezzlement, and up to 10-year jail sentences for four other senior Samsung executives.
Seven investigators seized documents on the renovations at the office located near the residences in central Seoul, police said.