Jesuit Father Hans Zollner, an internationally-renowned expert in protecting children and vulnerable adults from clerical sex abuse, has resigned from his position on the Vatican’s safeguarding commission.

The move was announced by the Pontifical Commission for the Protection of Minors on Wednesday.

The 56-year-old Zollner, a founding member of the commission, said in a statement March 29 that “structural and practical issues” within the commission had led him “to disassociate” from it.

“The protection of children and vulnerable persons must be at the heart of the Catholic Church’s mission,” he said. “That was the hope I and many others have shared since the commission was first established in 2014. However, in my work with the commission, I have noticed issues that need to be urgently addressed and which have made it impossible for me to continue further.”

In early March, Zollner was appointed a consultant to the Diocese of Rome’s new office for the protection of minors and vulnerable adults.

He is also the director of the Institute of Anthropology: Interdisciplinary Studies on Human Dignity and Care (IADC), hosted by the Pontifical Gregorian University.

The IADC, formerly called the Center for Child Protection, is an academic institute offering higher-education degrees in abuse safeguarding and anthropology.

In his statement, Zollner said he has “grown increasingly concerned” with the Vatican’s safeguarding commission and its lack of “responsibility, compliance, accountability, and transparency.”

“I am convinced that these are principles that any Church institution, let alone the Pontifical Commission for the Protection of Minors, is bound to uphold,” he said.

Hours before Zollner released his critique, a March 29 statement from Cardinal Sean O’Malley, president of the Vatican’s safeguarding commission, characterized the Jesuit priest’s departure as an effort to reduce his already significant administrative responsibilities, including  “his recent appointment as consultant for Safeguarding to the Diocese of Rome.”

“In light of this and all his other responsibilities, he has asked to be excused from his place on the commission and the Holy Father has accepted his request with the deepest of thanks for his many years of service,” O’Malley said.

The cardinal and archbishop of Boston praised Zollner’s “abiding presence over the years as we have seen our commission grow and find its way as the center for safeguarding throughout the Church.”

He also thanked the Jesuit for his hard work and extensive travels undertaken for the cause and said the commission looks forward to continuing to cooperate to make the Church a safe place for everyone.

The Pontifical Commission for the Protection of Minors, instituted in 2014, serves as an advisory body to the pope, providing recommendations on how the Church can best protect minors and vulnerable adults.

With the publication of Pope Francis’ apostolic constitution Praedicate Evangelium, the commission, which remains independent, was stabilized and given a more central role in the Roman Curia within the Dicastery for the Doctrine of the Faith.

The commission is led by O’Malley, president, and Father Andrew Small, OMI, secretary. It currently has 19 members.

In his statement, Zollner said he is unaware of any regulations governing the relationship between the safeguarding commission and the Dicastery for the Doctrine of the Faith.

He also said there was a lack of transparency about decisions in the commission, including problems with “insufficient information and vague communication” with members on how particular decisions were made.

“With regard to compliance, there has been a lack of clarity regarding the selection process of members and staff and their respective roles and responsibilities,” the priest also said. “Another area of concern is that of financial accountability, which I believe is inadequate. It is paramount for the commission to clearly show how funds are used in its work.”