The archbishop had previously revealed he received an email from the Dicastery for the Doctrine of the Faith informing him of the trial.
The deadline for Viganò to appear before the Vatican expired Friday.
The former papal nuncio to the United States — who garnered headlines in 2018 for alleging that senior Church officials covered up abuses committed by former cardinal Theodore McCarrick — has repeatedly rejected the authority of Pope Francis since then and has called on him to resign.
In a lengthy statement shared on social media June 28, Viganò accused Pope Francis of “heresy and schism” over his promotion of COVID-19 vaccines and his overseeing of the 2018 Vatican-China deal on the appointment of bishops.
He also said he has “no reason to consider myself separate from communion with the holy Church and with the papacy, which I have always served with filial devotion and fidelity.”
“I maintain that the errors and heresies to which [Francis] adhered before, during, and after his election, along with the intention he held in his apparent acceptance of the papacy, render his elevation to the throne null and void,” Viganò wrote.
Viganò, who has been in hiding for years, announced on social media June 20 that he had been summoned to Rome to answer formal charges of schism.
Schism is a canonical crime defined in the Code of Canon Law as “the withdrawal of submission to the supreme pontiff or from communion with the members of the Church subject to him.” Heresy, on the other hand, is “the obstinate denial or doubt, after baptism, of a truth which must be believed by divine and Catholic faith.”
The specific charges outlined against Viganò, according to a document he himself posted, involve making public statements that allegedly deny the fundamental elements necessary to maintain communion with the Catholic Church. This includes denying the legitimacy of Pope Francis as the rightful pontiff and outright rejection of the doctrines established during the Second Vatican Council.
Viganò had previously in a June 21 statement said he has “no intention of subjecting myself to a show trial,” further saying he has not sent any materials in his defense to the dicastery, “whose authority I do not recognize, nor that of its prefect, nor that of the person who appointed him.”