Rubén Villalba, a suspended Guardia Civil commander, testified before Spain’s Audiencia Nacional that Leire Díez, a former PSOE member, offered him a post as adviser to the director of the Guardia Civil or a position abroad. Villalba said the offer was made in exchange for sensitive information about the Central Operative Unit (UCO), the Guardia Civil unit responsible for investigating major corruption cases.
Villalba, who is under investigation in the so-called ‘caso Koldo’, told investigating judge Santiago Pedraz that he met Díez twice in March 2025. During those meetings, Díez allegedly offered to pay for his legal defense and help secure a senior Guardia Civil position if he assisted efforts to disrupt UCO investigations and provided information about basic personnel, anti-corruption prosecutors and businessman Víctor de Aldama. The Supreme Court sentenced de Aldama to four and a half years in prison for his role in the case.
Villalba said he rejected the offers and disclosed no confidential information. Documentation of the meetings, which he prepared, has been added to the case file. One position discussed was adviser to Mercedes González, then director general of the Guardia Civil. González has publicly acknowledged that Díez proposed Villalba for a post, but says she rejected the suggestion and denies involvement in any effort to undermine the UCO. She is scheduled to testify as an investigated party on July 16 and maintains that she did not participate in a plot against the anti-corruption unit.
The wider investigation before Pedraz concerns an alleged network linked to Díez and former PSOE organization secretary Santos Cerdán. Investigators are examining whether it sought sensitive information about judges, prosecutors, Guardia Civil officers and witnesses in politically sensitive proceedings, with the alleged aim of discrediting investigators and obstructing judicial proceedings. The inquiry is separate from the underlying caso Koldo, although it involves people and evidence connected to that case. Its scope also includes nine potential offenses cited in the proceedings, including criminal organization, disclosure of secrets, inducement to perjury, false accusation, document forgery, malfeasance, influence peddling and crimes against state institutions.
Investigative reporting has also detailed scrutiny of Díez’s contacts with Mercedes González, including a meeting at González’s official office in November 2024. Díez reportedly described González as someone she trusted and said she could approach her directly. Investigators are examining the contacts as part of their inquiry into possible efforts to obtain information through institutional relationships. The contacts alone do not establish that González took part in any alleged scheme.
The UCO is also examining whether professional-service contracts and payments linked to the PSOE financed or concealed activities attributed to Díez. The contracts under scrutiny include work involving lawyers Ismael Oliver, formerly counsel to Koldo García, and Jacobo Teijelo, counsel to Santos Cerdán, as well as consultancy services. Investigators are assessing whether the services were genuine or whether contracts and invoices covered other transactions. In October 2026, Judge Pedraz gave the PSOE 48 hours to provide contracts. The party missed the deadline, citing professional secrecy and confidentiality. At the time of that reporting, Pedraz had not formally designated the PSOE as an investigated party and was awaiting further investigative steps, including Cerdán’s testimony.
A separate investigative estimate put at least €43,225 in funds that investigators believed reached Díez through companies linked to former PSOE official Gaspar Zarrías and lawyer Ismael Oliver. The UCO has been examining the possible origin and handling of the funds, the engagement documents and invoices, including whether some invoices were false and whether the underlying work was carried out. The figure is an investigative attribution, not a judicially established loss or finding of criminal liability.
The investigation has also expanded to possible public-sector and commercial dealings involving Mercasa, a state-owned company majority-controlled by SEPI. Anti-corruption prosecutors reportedly cited investigative report 188/25 and alleged that people identified as Antxon, Leire and Vicente knew of plans concerning Mercasa’s headquarters and designed an operation intended to generate an economic benefit. Reporting connected the names to Antxon Alonso, Leire Díez and Vicente Fernández. This inquiry concerns possible irregular dealings alongside the allegations of obstruction; it does not amount to a final judicial finding of liability.
Villalba’s testimony was part of a series of statements ordered by the court. Patricia Espinar, co-founder of the digital outlet Crónica Libre, and Francisco Ortega, a Correos employee who arranged meetings between Díez and Villalba, also appeared before the judge that day. Both confirmed their previous statements to the UCO. Espinar distanced herself from the alleged scheme and described her role in a PSOE advertising campaign during the 2024 European elections, saying a colleague instructed her to invoice for online advertising services. Ortega confirmed that he knew both Villalba and Díez, and that Díez, his supervisor at Correos, asked him to arrange a meeting with the commander.
Investigators are also reviewing agendas and handwritten or recorded notes attributed to people connected to the alleged network. They are seeking to identify contacts, meetings and possible lines of inquiry ahead of further questioning. The materials concern a range of prosecutors and officials. Investigators are assessing their significance alongside testimony, documents and other findings.
Díez has rejected allegations about the UCO’s account and accused the unit of lying in its report. Asked about her meetings with González and whether González had warned her that the UCO was investigating her, Díez declined to give a substantive answer, saying she would speak when she had something to say. Her statements contrast with investigators’ reported focus on her contacts and alleged attempts to obtain sensitive information. The proceedings have not produced a final judicial determination resolving the competing accounts.
The case has drawn attention to the intersection of political influence and law enforcement in Spain, amid allegations of attempts to interfere with judicial investigations. Related coverage has examined scrutiny of the Guardia Civil’s leadership and the government’s response, including its decision to support Mercedes González despite ongoing internal probes, as reported in coverage of the government’s stance on the Guardia Civil director.
The UCO is basic to Spain’s investigations into corruption involving political and business figures. Pedraz’s inquiry brings together allegations of attempted interference, questions about professional contracts and payments, and a separate examination of possible dealings involving Mercasa. Its course will determine how the evidence, including Villalba’s account and the collected documents, is assessed in court.
