Two journalists and a high-ranking Vatican monsignor are amongst the group who have been question in connection with the latest so called 'Vatileaks' scandal.
Two members of the pope's reforms commission and a newly identified assistant were indicted on charges of disclosing confidential Vatican information and documents, while two journalists were indicted on a charge of soliciting and exerting pressure to obtain the information, according to the indictments released by the Vatican.
Monsignor Lucio Vallejo Balda and Francesca Chaouqui were arrested by the Vatican earlier this month.
The indictment also identifies for the first time an assistant to Balda, Nicola Maio, as under suspicion.
The three Vatican insiders also face an additional charge of forming a criminal organisation.
It comes after Journalists Gianluigi Nuzzi and Emiliano Fittipaldi (pictured above) published books appearing to outline instances of greed and financial abuse at the Vatican.
The books cited official Vatican documents as proof.
Nuzzi, who refused a Vatican summons for questioning, was defiant in a message on Twitter.
"You can do what you want but as long as the world exists, there will be journalists who report uncomfortable news," he wrote.
Fittipaldi appeared for questioning but refused to give any answers, citing Italian law on protecting sources.
If the Vatican tribunal ultimately convicts the two authors, it will come down to a political question as to whether the Holy See will request their extradition from Italy - and whether Italy will oblige.
Trial is set to begin on Tuesday. After formalities, the trial is expected to resume the following week.
The trial will be open to the press, as was the case previously in the case of documents leaked during the papacy of Benedict XVI.