The Koldo corruption case concluded on Wednesday in Madrid, with evidence from its three main characters; former transport minister José Luis Ábalos, his ex-aide Koldo García and businessman Víctor de Aldama. But it was the testimony heard on Tuesday that dealt what must surely be the fatal blow to Pedro Sánchez's credibility: in a ten-hour session at the Supreme Court, two senior officers in the Guardia Civil's central operations unit (UCO) painted a picture of a vast, sophisticated network of bribery within Sánchez's government, reaching all the way up to the prime minister.

According to Lieutenant Colonel Antonio Balas, head of the UCO's economic crime unit, Ábalos played a "fundamental" role in a criminal group led by Aldama, which allegedly enabled the former minister and his then-aide García to pocket substantial bribes for awarding face mask contracts during the pandemic.

"The ministry is the one with the influence, the one that opens doors...the one with the power to take Aldama and his associates to high-level places they could never reach on their own," claimed Balas: "That's why [Ábalos] charges what he charges...and when he demands payment, they pay him."

Balas's explosive testimony was corroborated by that of Commander Montes, revealing a bribery network that had access to the "highest echelons of power". Most damningly, Balas said that it "even had access to the prime minister".

As if that weren't bad enough, investigative journalist Ketty Garat had a new book published in Spanish on Wednesday - entitled All Sánchez's men: how the biggest corruption plot in Spain's democratic history was organised. Garat claims that Sánchez deployed Santos Cerdán, the PSOE's former organisational secretary, as an "emissary", to deflect attention from corruption within the party as a whole by dishing dirt on Ábalos, including his predilection for prostitutes (of which the prime minister was apparently aware). According to Garat, "Sánchez knew everything."

Remarks made by Sánchez last June, when Cerdán resigned in connection with the Koldo case, now take on a somewhat different meaning. Apologising to the public for having trusted Cerdán, the Socialist leader made the extraordinary remark that "there is no such thing as zero corruption, but there must be zero tolerance when it takes place". Here was the prime minister of Spain effectively saying that it is unrealistic to expect any government - or at least any Spanish government - to be entirely clean. And, if Garat is correct, completely misrepresenting his relationship with Cerdán.

Attempting to distance himself from Cerdán, Sánchez also said that "This is not about me, and it's not about the Socialist party" - a claim which now seems equivalent to saying that Gürtel wasn't about the PP. The testimony heard this week, at the dramatic conclusion of a case that should bring down his government, shows otherwise.