The claim surfaced this week in a Bloomberg profile of jailed Colombian political operative Andrés Sepúlveda, who, as the piece describes, managed teams of hackers to both generate fake social media trends, and to steal emails, strategy plans, and other internal documents of opposition candidates. Sepúlveda gives Bloomberg details of his black-hat work on campaigns in Colombia, Honduras, Nicaragua, and Mexico, where he says he played a role in the recent election of President Enrique Peña Nieto. Sepúlveda is now serving a ten-year sentence for espionage and hacking.

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Rendón nonetheless maintains that he never employed Sepúlveda, and has denied other accusations of wrongdoing. But Sepúlveda showed Bloomberg an array of email exchanges with Rendón that show evidence of them working together, and which Bloomberg says appeared genuine when vetted by an expert.

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There is a big caveat to this story. Rendón has multiple motivations to lie about being contacted by the Trump campaign, not least, raising his own profile as an operative. He has also said he dislikes Trump, possibly thanks to the same rhetoric that has turned American Latinos against the candidate. Linking himself to Trump publicly could be seen as yet another act of political sabotage—even if his denials of criminal activity are true, Rendón must know that being associated with him could harm an American presidential campaign.

In fact, Rendón told Bloomberg he is now in talks with another leading presidential campaign—but declined to say which.