But for many Mexicans, the case represents something far greater than 43 people: It is a window onto the tens of thousands of others who have also disappeared during the nation’s decade-long drug war, and the anguish visited on their families. Caught between cartel violence and a government either unwilling or unable to help, they are victims twice.

The arrival of the international experts inspired hope and a shot at closure, if only vicariously, for those who suffer their losses quietly on the margins of Mexican society. In an exceptional gesture, Mexico was granting foreigners permission to conduct a true investigation. Now their departure is a bitter one.

“This is something that will probably haunt us for a long time,” said Francisco Cox, a Chilean human rights lawyer and another member of the group of experts. “But it didn’t make sense to stay here, because in a certain way it’s giving legitimacy to something deep inside you know isn’t right.”

Though the group’s final report will be issued on Sunday morning, the case is far from solved. The remains of only one of the 43 has been found and identified; the rest are all still missing.

Another question is how high the collusion between the drug gangs and the government goes. Although the government’s own investigation focused on the complicity of the local authorities, the expert panel uncovered evidence that state and federal officials and even military personnel were present on the night of the students’ disappearance.

“It was clear in the government’s investigation and the official account that there was an intention to keep this case at a municipal level, in terms of responsibility,” said Carlos Beristain, another expert in the investigation. “But we revealed the presence of state and federal agents at the crime scenes, and furthermore that their participation implied responsibility.”