Mexico has asked Interpol to issue a red notice for a former official who spearheaded a controversial probe into the 2014 vanishing and suspected murders of 43 student teachers, Reuters reports. The country’s attorney general’s office put out the call for the arrest of Tomas Zeron after parents of the victims and experts accused him of manipulating the investigation. Zeron, who has denied wrongdoing and resigned from his role on 2016, is reportedly thought to be in Canada.

At the time of the disappearances, then-President Enrique Pena Nieto’s government claimed the 43 individuals had been killed by a drug gang after mistaking them for a rival group. According to that account, their remains were burned and dumped in a nearby river. Zeron’s team claimed they found a bone fragment belonging to one of the students in the river, but independent experts said Zeron had gone to the river a day before with an alleged gang member. It is believed the supposed murders were the work of corrupt police forces working in tandem with a drug gang, and current President Andres Manuel Lopez Obrador’s administration has said they will investigate the original handling of the probe.