A panel of independent experts has accused the Mexican government of obstructing an investigation into the 2014 disappearance of 43 students. The report casts doubt on the government’s ability to carry out justice in the case.

The Interdisciplinary Group of Independent Experts (GIEI) said Thursday that federal prosecutors repeatedly undermined an investigation into the forced disappearances of the students from the Ayotzinapa teachers college in the state of Guerrero.

And they say the resignation this week of the special prosecutor stems from that interference.

The GIEI’s Francisco Cox says the Attorney General’s Office hindered the investigation from the start — ignoring requests for warrants and reports, carrying out arrests without the special prosecutor’s knowledge and withdrawing nearly two dozen arrest warrants, including 16 for members of the military.

The group also presented evidence that the military was in communication with members of a cartel allegedly involved in the students’ abduction.