Antoine Griezmann negotiated a €14m commission to agree a move to Barcelona in March four months ahead of his move, report El Mundo.
Blagurana club officials paid his €120m release clause at La Liga headquarters in Madrid in July, although Atleti allege that the signing had been done before the clause dropped to €120m from €200m, on 1 July.
A subsequent statement from Atleti alleged that they would take the Catalan giants to court over the deal, which they believe they can prove was agreed before the clause dropped.
The newspaper now claims it has access to multiple emails which claims that his sister and agent, his father and a key mediator from the Catalan club were the beneficiaries from the talks.
Earlier this week, El Mundo also claimed Juantxo Landaberea is now carrying the case, as outlined by the report, and believes that Barcelona might be hit by a stadium ban as appropriate punishment for breaking the rules, should they be found guilty.
Atletico can no longer drop the case under Spanish law, since they initially filed it, and the stadium ban punishment is outlined in articles 88 and 126 of the federal disciplinary code.