Suu Kyi, 64, is charged with violating the terms of her house arrest by harboring an uninvited American man who swam to the Nobel Peace Prize laureate's lakeside home and stayed for two days. She faces a possible five years in prison.
Suu Kyi's lawyer Nyan Win said he expected the verdict to be delivered in two to three weeks.
The government official, who demanded anonymity since he was not authorized to speak to the press, said the lawyer for American John W. Yettaw, 53, of Falcon, Missouri, gave his final arguments. Two female companions of Suu Kyi presented statements before the court.
Diplomats from the United States, Singapore, Australia, Japan, the Philippines and Malaysia were allowed to attend the morning session but not the key afternoon one where the prosecution's arguments were to be heard, one of the diplomats told reporters.
However, authorities allowed U.S. Consul Colin Furst to be present in the afternoon because an American was standing trial.
Yettaw is also charged with violating terms of Suu Kyi's house arrest - as an abettor - and could be sent to jail for five years. He also faces a municipal charge of swimming in a non-swimming area and is accused of immigration violations.
Yettaw's lawyer will argue that the American only committed criminal trespass, since he entered house late at night. That charge carries a maximum jail term of three months.
Yettaw has pleaded not guilty and explained in court that he had a dream that Suu Kyi would be assassinated and he had gone to warn her.
"I will try my best to defend my client. I will argue that he did not violate the restriction order and I will try my utmost to get him lesser punishment," Khin Maung Oo, Yettaw's lawyer, said over the weekend.
Tried on the same charges as Suu Kyi are Khin Khin Win and her daughter Win Ma Ma, who have long been Suu Kyi's companions during her house arrest. Both are members of Suu Kyi's National League for Democracy party.
The trial has drawn condemnation from the international community and Suu Kyi's local supporters, who worry the ruling junta has found an excuse to keep her behind bars through elections planned for next year.
At an Asia-Pacific security forum last week, U.S. Secretary of State Hillary Rodham Clinton offered Myanmar the prospect of better relations with the United States, but said that depended in part on the fate of Suu Kyi.
Myanmar state media rejected the criticism, accusing Clinton and others calling for Suu Kyi's release of "interference."
The trial started May 18. The court had approved 23 prosecution witnesses, of which 14 took the stand. Only two out of four defense witnesses were allowed.
Myanmar, also known as Burma, has been under military rule since 1962.
Suu Kyi's opposition party won national elections in 1990, but Myanmar's generals refused to relinquish power. Suu Kyi has been under house arrest for 14 of the past 20 years.