This post has been updated.

D.C. Attorney General Irvin B. Nathan said bus drivers employed by the Office of the State Superintendent of Education are among the top 10 offenders in a scheme to collect unemployment benefits while still holding their jobs.

D.C. Attorney General Irvin B. Nathan in his office in July. (Bill O'Leary/WASHINGTON POST)

On Monday, the District government suspended nearly 90 employees for receiving the payments. Another 40 former employees were also implicated. City officials estimate that $800,000 in benefits were doled out to working city employees since 2009.

“The most egregious cases will be referred to prosecutors,” Nathan said at the mayor’s bi-weekly news conference Wednesday.

Nathan said workers who received payments signed documents claiming that they were unemployed, which would put them in violation of the city’s False Claims Act.

“In every case, we will try to get the money back,” he said.

Nathan said there does not appear to be a “ring leader or collusion.” Instead, employees saw a hole and took advantage, he said.

Lisa Mallory, director of the D.C. Department of Employment Services, said some employees have already been terminated since Monday but she did not know how many.

She said most employees were placed on administrative leave, stretching to 15 or 30 days, depending on their contracts.

Nathan said the city did not want to risk lawsuits from employees who could claim that the city did not follow policy in their terminations. Each employee has been given the opportunity to “explain in writing what happened,” he said.

“We are going to give them due process,” he said.

Mayor Vincent C. Gray (D) attributed the alleged fraud to poor supervision of the benefits program in the past. “The controls were insufficient,” he said.

Mallory said a U.S. Department of Labor grant allowed the employment agency to install the technology and increase controls that began detecting fraud last year.