MEXICO CITY (AP) — Mexican prosecutors have filed fraud charges against a businessman linked to a $400 million loss at Citigroup’s Mexican bank subsidiary.

Citigroup subsidiary Banamex recently fired 11 employees for not following proper procedures in dealing with the Oceanografia oil services company formerly headed by businessman Amado Yanez.

Yanez had been under a form of house arrest while under investigation.

The arrest warrant announced Thursday would normally mean a suspect is sent to prison while a judge decides whether to hold him over for trial.

However, the attorney general’s office said Yanez is under police guard at a hospital where he is recovering from surgery.

In February, Banamex announced that Oceanografia had used falsified invoices as collateral to obtain $585 million in loans. Citigroup could verify only $185 million of invoices.

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