For well over a year now, Mexicans have vowed not to forget the 43 missing students from a small teaching college in Ayotzinapa, in the southern Mexican state of Guerrero. The tragedy has become one of the most notorious human rights cases in Mexico in recent years.

On Sunday, more than 1,000 people gathered to hear from an international panel of investigators who have looked into the case. Many in the crowd counted aloud to 43 as they waited.

The main finding from the foreign experts, commissioned by the Inter-American Commission on Human Rights, is clear: Mexico's government stonewalled their investigation into the student's apparent massacre in 2014. Despite that interference, the experts did cast doubt on several aspects of the government's version of events.

— View their presentation.

— Read the panel’s two reports.

Similar to the commission's first report, the second report blasts the Mexican government’s own investigation. That official version, which the government calls the "historical truth," says corrupt local police handed the student teachers over to a criminal drug gang, and that the students were incinerated at a garbage dump in Guerrero.

The independent foreign experts fundamentally disagree with that account, saying that many lines of investigation remain unexplored. "The delays in obtaining evidence that could be used to figure out possible lines of investigation translates into a decision [to allow] impunity," the report said.

The investigators also revealed that federal and state police were patroling in Iguala the night the students disappeared, but have not revealed details about their mission. The experts also found that Mexico's army kept key evidence from the experts, including photographs and video footage of the police clashing with the students.

Investigators' requests to interview members of the military were consistently denied.

International probe shows Mexican police were all over the "disappearance" of 43 students. https://t.co/Z0Dqk4jPEJ pic.twitter.com/9qMt80M1BO — Kenneth Roth (@KenRoth) April 25, 2016

Experts: Mexico Stonewalled Investigation into Killing of 43 Students... https://t.co/504e3OWNUc — Dallas daily (@epeakdallas) April 25, 2016

After the experts presented their findings, Mexico’s President Enrique Peña Nieto tweeted that he appreciated the international commission and its recommendations. Mexican government officials have maintained they are fully cooperating with these outside experts.

And yet, no government representatives attended the conference in Mexico City where the report was published.

Many Mexicans, most of all the families of the missing 43, are frustrated to see the independent investigation coming to a halt. "There seems to be no limit to the Mexican government's utter determination to sweep the Ayotzinapa tragedy under the carpet," Amnesty International's Erika Guevara-Rosa said in a statement.

After releasing their reports, the experts will soon leave Mexico. Their contract with the Mexican government wasn't extended past its April 30 expiration.