Robert Petit, the Canadian prosecutor for the Khmer Rouge tribunal, will resign his post, saying in a statement Tuesday he was leaving Sept. 1.

“It is with the deepest regret that, for personal and family reasons, I must demit my position as International Co-prosecutor,” Petit wrote in a statement.

Petit has been at odds with his Cambodian counterpart, Chea Leang, over whether to indict more leaders of the Khmer Rouge, claiming more indictments could be prosecuted under the UN-backed court.

Chea Leang argues that more arrests could destabilize the country, echoing statements made in public by Prime Minister Hun Sen.

“I remain convinced that Cambodia’s hopes for a better future lie, in part, on true accountability for crimes,” Petit said in his statement. “My staff and I have tried, within our jurisdiction, to contribute to that goal to the best of our abilities.”

The resignation comes in the middle of the trial of Kaing Kek Iev, or Duch, in the tribunal’s Case No. 001, and ahead of a trial for four other jailed leaders, Case No. 002. Further indictments would bring up a third case.

“We are concerned about the continuity of the court, especially for Case No. 002, which is under investigation, and how will go Case No. 003, proposed by Robert Petit,” said Long Panhavuth, a tribunal monitor for the Open Society Justice Initiative.