ATHENS, Greece — A prosecutor on Greece’s Supreme Court is set to intervene in a case of educational fraud that has roiled the country and united political parties, labor unions and rights groups: A 53-year-old cleaner is serving 10 years in prison for falsifying her primary school diploma to get a public sector job.

An initial court ruling two years ago handed the woman a 15-year prison term for defrauding the public; the sentence was reduced this month, and she has been in Thiva prison in central Greece ever since.

An online petition for her release had drawn more than 20,000 signatures by Friday afternoon.

“This decision is not simply inhumane,” the Hellenic League for Human Rights said of the decision to sentence her to jail for 10 years. “It is another very indicative sign of permanent ailments in the criminal justice system.”

The unidentified cleaner had worked at a state kindergarten in Volos, in central Greece, for 18 years, until a review in 2014 revealed that she had doctored a certificate to show she had completed six years of primary education (roughly elementary level) instead of only five. Six years is the required term for primary school students to complete their education.