The special prosecutor leading an investigation into 43 missing students in southern Mexico has resigned. There are concerns about the implications of his resignation for the future of the case.

For more than three years, Omar Gomez Trejo has led a probe into the 2014 disappearance of 43 students from the Ayotzinapa teachers college in the state of Guerrero.

There have been recent advances in the case, including arrests of high-profile former officials.

But on Monday — the eighth anniversary of the students’ abduction and disappearance — Gomez Trejo resigned.

His resignation comes as the Attorney General’s Office has received backlash for canceling 21 arrest warrants — including 16 for members of the military. And after an unredacted report was leaked to the press.

President Andrés Manuel López Obrador said Tuesday that the prosecutor quit over disagreements about the process of securing arrest warrants.

Families of the missing students have called for the resignation of the Attorney General Alejandro Gertz Manero, but Gomez Trejo seems to have gained their trust.

A human rights group that has represented the students' families put out a statement calling the resignation extremely worrisome, and some experts have expressed concern that recent developments cast doubt on the government’s willingness to take on politicians and the military, especially as Lopez Obrador continues to consolidate power in the army.