Mexico said Monday that it had asked Israel to detain a former top investigator into the murky disappearance of 43 students in 2014 in a case that shocked the country.

Tomas Zeron, who was head of the Criminal Investigation Agency, is wanted over allegations of serious irregularities in the probe into one of the country's worst human rights tragedies.

In July, Mexico said Zeron was in Canada and that it was seeking his extradition, but President Andres Manuel Lopez Obrador said Monday that he was now believed to be in Israel.

"The government of Israel could not, I mean it respectfully, give protection to a person with these characteristics," Lopez Obrador told reporters.

"It would not be fair or humane because there are sufficient elements to show that he acted improperly."

Tomas Zeron (pictured in a September 2015 handout photo), who was head of Mexico's Criminal Investigation Agency, is wanted over allegations of serious irregularities in the probe into one of the country's worst human rights tragedies
Tomas Zeron (pictured in a September 2015 handout photo), who was head of Mexico's Criminal Investigation Agency, is wanted over allegations of serious irregularities in the probe into one of the country's worst human rights tragedies GENERAL ATTORNEY'S OFFICE / HO

Zeron is one of the architects of the so-called "historical truth," the official version of the case presented in January 2015 by the government of then-president Enrique Pena Nieto, which was rejected by the victims' families.

The disappearance of the teaching students in 2014 sent shockwaves around Mexico.

They had commandeered five buses to travel to a protest, but were stopped by corrupt police in the city of Iguala, Guerrero and handed over to a drug cartel.

Prosecutors initially said the cartel mistook the students for members of a rival gang and killed them before incinerating their bodies at a garbage dump and tossing the remains in a river.

However, independent experts from the Inter-American Commission on Human Rights rejected the government's conclusion, and the families of the victims continue to demand answers.