The teacher, aged 47, is accused of using his position of authority to demand sex from around a dozen students – some as young as 15 – at the Eleonora d’Arborea high school in Cagliari.
Students who refused his advances were continually harassed by the teacher and punished with low grades while those who agreed to have sex with him scored top marks, the local newspaper Unione Sarda reported.
Among the accusations, the man allegedly raped a minor in a classroom at the school while her classmate guarded the door.
In another incident, he is accused of blackmailing a student into having sex with him, threatening to reveal that she was gay to her parents.
He is also alleged to have sent explicit text messages to some of the students demanding sex.
According to La Stampa, the teacher was first reported to police three years ago by a few teachers on behalf of a student, although the alleged crimes date back to 2005. The teacher, however, continued working at the school.
The scandal erupted in March this year when a group of parents accused the teacher of “teaching sex instead of maths”, unaware that he had been under investigation for three years.
Quoted by Italian news agency Ansa, the school’s headmaster Antonio Piredda said that Melis had been suspended from teaching three times in the past year, with the latest suspension set to expire on October 6th.
The teacher is now being held under house arrest as the investigations continue.