Spanish justice announced today the opening of an investigation into “negligent homicide” after the fire that occurred on Sunday in a night club in Murcia (southeast), in which 13 people lost their lives.

An investigator from the court of Murcia “will be placed in charge of the investigation with the aim of ascertaining the facts and determining, where appropriate, criminal responsibilities,” the court said in a statement.

Two nightclubs destroyed by deadly fire were found to be operating without a license a year ago and ordered closed, local authorities said today.

It is not clear why the clubs were allowed to continue operating after this recommendation. The fire in the early hours of Sunday morning was the deadliest in decades in Spain.

The fire affected three adjacent nightclubs in Atalayas, on the outskirts of the city, but two of them — the Teatre and the Fonda Milagros — were the worst hit. The causes of the fire remain unknown.