During his closing argument in the trial in New York state court, lawyer Kevin Marino said it was undisputed that Sergey Aleynikov copied code from Goldman’s high-frequency trading software for his own use in June 2009, violating the bank’s confidentiality policy.

“There’s no doubt that Mr. Aleynikov did something wrong,” Marino said.

However, he said prosecutors failed to prove that Aleynikov violated state law, which requires showing that Aleynikov took "the major part" of the code's value for himself.

Goldman continued to make money using the code, and prosecutors presented no evidence that Aleynikov received any value from it, Marino said.

But New York Assistant District Attorney Daniel Holmes said it did not matter that Aleynikov had failed to realise the full value of the code he copied.

“This is a case about a man taking something that he had no right to take,” he said. “It’s that simple.”

The arguments capped a two week-trial in a case that inspired Michael Lewis' best-selling book "Flash Boys."

Prosecutors say Aleynikov, a dual citizen of Russia and the United States, stole the computer code as he prepared to leave Goldman for a high-frequency trading startup in Chicago.

Aleynikov, 45, first arrested by federal agents in 2009, was previously tried and convicted in federal court. An appeals court threw out the conviction in 2012, saying the anti-espionage law did not apply and setting Aleynikov free after about a year.

About six months later, Manhattan District Attorney Cyrus Vance revived the case in state court and charged Aleynikov in August 2012 with unlawful duplication of computer-related material.

Aleynikov faces 1-1/2 years to four years in prison if convicted on state charges.

(Reporting by Brendan Pierson; Editing by Noeleen Walder and Leslie Adler)

By Brendan Pierson