ATLANTA — After more than five years of controversy and five months of testimony, a prosecutor used seven words on Monday to recap the accusations against the dozen Atlanta educators seated in a courtroom here.

“They cheated,” the prosecutor, John E. Floyd, told the jurors in Fulton County Superior Court. “They lied. And they stole.”

Mr. Floyd’s scornful summary came near the start of what will be days of closing arguments centered on whether significant increases in standardized test scores in Atlanta’s public schools came about because of endemic cheating and what prosecutors say was criminal misconduct that included racketeering. The trial, set up by a March 2013 indictment, as well as a state-commissioned report and a series of articles published by The Atlanta Journal-Constitution, could lead to decades in prison for the defendants.

And with the death this month of Beverly L. Hall, the longtime Atlanta superintendent who was also charged and was to stand trial separately, the proceedings have taken on the burden of being the climax of the scandal that embarrassed this city.