The European Public Prosecutor’s Office is investigating possible fraud involving EU funds for safety, signaling and communications upgrades on Spain’s rail network following a fatal train crash last month.

The EPPO has launched a probe on Spain’s Madrid-Seville high-speed railway line, where 69 people were killed in a collision near Urda, in Toledo province, on Oct. 28. Óscar Puente, who has since resigned as transport minister, said a computer failure followed by human error caused the crash.

Investigators for the EPPO carried out on Friday searches at Adif, the state rail infrastructure manager, the State Railway Safety Agency and the Spanish Court of Auditors, with support from national authorities.

The EPPO did not clarify what investigators are looking for or whether any money was misspent, and no findings have been made public. It added that no further details would be released at this stage.

A first probe, opened in March after the Adamuz crash that killed 46 people, covered EU funds for track maintenance on the same line. There has been no public update on its progress.

The EU’s Transport Commissioner Apostolos Tzitzikostas expressed deep concern at a press briefing on Wednesday over two serious accidents in Spain within a year, calling them “very worrying” and “definitely not something we want to see.” He noted that Spain had reached out to the EU’s railway agency, ERA, to assist with the ongoing national investigation.

Two senior Spanish officials have already stepped down following the Urda crash. Puente resigned Tuesday, calling his decision “a matter of political dignity,” while Adif President Luis Pedro Marco de la Peña quit Wednesday, less than 24 hours later.

Economy Minister Carlos Cuerpo is running the Transport Ministry until the Nov. 29 election. The crash took place just weeks before the vote, with Prime Minister Pedro Sánchez’s Socialists already trailing in the polls and facing further political fallout over the tragedy.