Costa Rica’s attorney general has begun an investigation into the disappearance of nearly 6 million euros from the coffers of the Central American state’s largest commercial bank, its acting chief executive announced Tuesday.

An amount of 3.3 billion colones (5.8 million euros) was revealed missing from the coffers of the National Bank of Costa Rica (Banco Nacional de Costa Rica, BNCR) in August, during an internal audit.

Five members of the staff of the credit institution were made available when it was found that the amount was lost, BNCR chief of staff Jaime Murillo explained during a press conference.

The attorney general’s investigation focuses on these five individuals, which include a member of the accounting department, supervisors and a security guard.

“We cannot say with certainty that this is a case of fraud, or that someone stole this money. We’re not there yet.” the case is “being investigated”, Mr. Murillo emphasized, speaking of an unprecedented situation in the 109 years that the bank has been operating.

The interim head of BNCR also tried to reassure the public, assuring that the savings and other investments of its customers are not at any risk.

The bank’s management says it still does not know when or how the amount could have been “lost”, adding that expects things to become clear after the investigation is completed of the General Prosecutor’s Office and its own, internal investigation at the same time.