A key suspect in the 2014 Mexico college student killings was given over to Mexican officials by American authorities after he attempted to cross the border without the required documentation.

The man was initially only named by his first name by Mexico's National Immigration Institute, but a federal agent verified Thursday to The Associated Press that he is, in fact, Alejandro Tenescalco. He was deemed ineligible for U.S. asylum, according to the institute.

The former Mexico police, Tenescalco, was apprehended on December 20 while attempting to enter the United States illegally.

During his time as a supervisor in Iguala, Chilpancingo state, he was responsible for the detention of college students attending a university for rural educators.

The Mexican government has speculated that the students were slaughtered and burned to death by a criminal gang that was given their information by corrupt Mexico police.

Government Truth Commission director Alejandro Encinas has identified Tenescalco as "one of the main perpetrators" of the crime.

There are kidnapping and organized crime charges against him. The Mexican government had offered a reward of $500,000 for his capture.

The murders of the students sparked anger throughout the world and symbolized the systemic violence and corruption that plagued Mexico.

Three military personnel, including a now-retired general who oversaw the local army when the abductions took place, were arrested because of the investigations.

Then-federal Attorney General Jes Murillo Karam allegedly made up the original official account through torture and manipulation of evidence.

Tainted evidence has led to the dismissal of charges against scores of other suspects.

READ NEXT: 43 Missing Ayotzinapa Students 

Mexico College Student Killings Was Declared a 'State Crime'

Military personnel was responsible, either directly or via incompetence, for the disappearance of 43 students in 2014, according to a truth commission probing one of Mexico's biggest human rights tragedies.

As international human rights experts criticized the official inquiry as being riddled with errors and abuses, the mass disappearance of the students provoked international indignation about impunity in Mexico. It damaged the administration of then-President Enrique Pena Nieto.

Encinas finally admitted publicly in August 2022 that the students had perished, per Al Jazeera.

At a press conference, Encinas said that "state crime" was committed by municipal, state, and federal officials involved in the disappearance.

"Their actions, omissions or participation allowed the disappearance and execution of the students, as well as the murder of six other people," said Encinas, claiming that there is no sign that they are alive as all evidence and testimonies prove that they were killed and disappeared.

"It's a sad reality," he added.

Encinas reported that despite intense searches, just three students' bodies had been located and identified.

What Happened to the Victims of Mexico College Student Killings

The 43 attended an all-male teacher training college in Ayotzinapa, Guerrero state's westernmost municipality.

Students at this university have a long history of leftist activism and hold frequent protests, according to BBC.

They traveled in huge numbers to the neighboring town of Iguala on September 26, 2014, to demonstrate against what they viewed as biased recruiting processes for teachers.

As they rode the buses back to school, they were ambushed by local Mexico police officers, who opened fire.

As a result of the ensuing chaos, six people lost their lives. Some students made it out alive, but 43 were never seen again after the fight.

Under then-President Enrique Pea Nieto, a preliminary official inquiry determined that the 43 had been taken by corrupt local Mexico police officers and then turned over to members of the local drugs gang Guerreros Unidos (United Warriors).

The group reportedly brought the victims to a garbage dump in Cocula, where they murdered and burned their bodies.

The report determined that their remains were thrown into a nearby stream.

Unfortunately, the credibility of that report has since been called into question, and a court has issued an arrest warrant for Tomás Zerón, the investigator in charge, who has already fled Mexico.

READ MORE: El Chapo Seeks Mexico Return 

This article is owned by Latin Post.

Written by: Bert Hoover

WATCH: "A Crime of the State": Mexico's Attorney General Arrested in Case of 43 Missing Ayotzinapa Students - From Democracy Now!