Former state probation commissioner John O'Brien was convicted of federal racketeering and mail fraud in a case that accused him of rigging the department's hiring process to favor politically-connected applicants over more qualified ones.
The verdict was returned on Thursday after seven days of deliberations in a case that focused attention on the patronage culture in state government.
The jury also convicted one of O'Brien's former deputies, Elizabeth Tavares, of racketeering and mail fraud.
Federal prosecutors said the defendants created a "sham" system to make it appear candidates were being hired for jobs in the probation department on merit, when in fact they were getting jobs because they had been sponsored by powerful state lawmakers.
Defense attorneys claimed the government did not prove during the two-month trial that any laws had been broken.