An ex-cop was recently extradited by U.S. authorities to Mexico for his suspected involvement in one of the most heinous and contentious crimes in recent Mexican history. In 2014, 43 students from the Ayotzinapa Rural Teachers’ College vanished in the city of Iguala, located in the southwestern state of Guerrero.

Along with the students’ disappearance, six other people were killed. The case has been shrouded in secrecy and has been marred by accusations of government cover-ups and collusion between criminal organizations, local and state police, and the military.

Alejandro Tenescalco Mejía, 41, allegedly played an instrumental role in the scandal, but he disappeared shortly after the incident. The Mexican government has since offered a 10 million peso reward, or roughly $530,000 USD, for information that led to his capture.

In mid-December, however, Tenescalco Mejía was arrested attempting to illegally climb over a border wall into the U.S. close to El Paso, Texas, the U.S. Immigration and Customs Enforcement (ICE) said in a statement. He was extradited to Mexico last week.

On September 26, 2014, Ayotzinapa students commandeered several buses to transport their peers to a protest in Mexico City. Students from the school, which has a long tradition of activism, are known for appropriating buses, and local transportation companies generally tolerate the practice. But when the students took the buses that night, they were stopped by police officers, then disappeared. What happened next is still unclear.

Tenescalco Mejía worked as a police supervisor in Iguala on the night of the disappearances, and his name routinely came up in both state and private investigations into the case. In 2015, a court issued an arrest warrant for Tenescalco Mejía, who promptly disappeared. The Mexican government declared him “one of the main perpetrators involved in these acts of forced disappearances” and announced the reward for his capture in 2019.

Authorities alleged that Tenescalco Mejía was at various sites around Iguala on the night of the disappearance and may have been coordinating the local police at others. Within weeks of the disappearance, the federal government alleged that Iguala cops turned the students over to a local cartel called the Guerreros Unidos, who murdered the students and burnt their bodies at a local garbage dump. But the official line quickly came under question, with allegations of the involvement of the military in the disappearances.

President Andrés Manuel López Obrador promised to finally bring closure to the case after he took office in 2018 and appointed a truth commission to revisit it. In August 2022, the truth commission released their findings and formally declared that there had been an organized cover-up.

“At all times the federal, state and municipal authorities had knowledge of the students’ movements,” the truth commission wrote. “Their actions, omissions, and participation allowed for the disappearance and execution of the students, as well as the murder of six other people.”

Since then, three members of the army have been arrested, including a general, along with the former Mexico Attorney General Jesús Murillo Karam, who allegedly spearheaded the cover-up.

But even with the renewed investigation into the case, the new findings have also come under question. The lead investigator who led the truth commission later stepped down due to concerns about the procedures that were followed in obtaining the new arrest warrants. The arrested military officers continue to maintain their innocence. The families of the students continue to wait for justice, as only the partial remains of three of the students have ever been found.

The arrest of Tenescalco Mejía could help bring closure to the case, if he chooses to cooperate with investigators.

Carlos Beristáin, a member of a group of outside investigators who have led the way in blowing apart the government’s initial theory into the disappearance, told Spanish newspaper El Pais that Tenescalco Mejía could be a key link in tying together what really happened that night. “We have insisted on capturing him since our first report [in 2015]. He is someone pivotal to that night.”