Greece’s Supreme Court prosecutor has moved to challenge the conditional release of Alexandros Giotopoulos, the convicted leader of the now-defunct militant group November 17, placing the ruling under judicial review, officials said.

Deputy Supreme Court Prosecutor Sofoklis Logothetis filed an appeal seeking to annul the decision that allowed Giotopoulos’ release, arguing that legal requirements were not met.

According to the prosecutor’s assessment, Giotopoulos has not served the minimum time required for inmates sentenced to multiple life terms, and no substantial change in circumstances justifying release has been demonstrated.

The case will now be examined by a judicial council of the Supreme Court, which will decide whether to uphold or overturn the lower court ruling. If the appeal is accepted, the release order will be cancelled and Giotopoulos could be returned to prison. The hearing is expected to be scheduled in early June.

Giotopoulos, 82, was released last week from Korydallos Prison in Athens after serving about 24 years in custody, following an appellate court decision granting conditional release.