A federal judge in New York has admonished prosecutors involved in a long-running case against an Iranian banker who was convicted on sanctions violations, saying that numerous missteps raised “serious concerns” about the US government’s conduct. Judge Alison Nathan called on the US attorney’s office in New York, which led the case on behalf of the Department of Justice, to submit detailed information to the court about individual government attorneys – and their supervisors – who had made false statements to the court in the case, and other allegations of prosecutorial misconduct. The admonition came just days after the chief prosecutor in the case made a rare request to dismiss the case against the convicted banker, Ali Sadr Hashemi Nejad, citing “disclosure-related” issues that had come up in the case before and after the March 2020 conviction. Legal experts told the Guardian that it was a bizarre decision in a protracted case involving an individual from a prominent Iranian family. Just three months ago, Geoffrey Berman, the US attorney for the southern district of New York, said that a jury’s decision to find Sadr guilty of fraud and conspiracy showed that “US sanctions are for real, and violators will be exposed and prosecuted”. At the heart of the conviction were claims by the US government that Sadr had created a network of front companies and bank accounts to mask Iranian business dealings with Venezuela, and funnel the proceeds of a Venezuelan construction project through US banks. The US government had argued that Sadr had used front companies in Switzerland, Turkey, and St Kitts & Nevis to conceal the movement of $115m in payments to his family in Iran, including his father Mohammed Sadr, a prominent Iranian businessman. Last week, Berman changed course on the case, saying it “would not be in the interest of justice to further prosecute the case” after Sadr’s lawyer raised issues about information that had not been disclosed to his solicitors during the trial. Iran experts and former prosecutors who discussed the matter with the Guardian on the condition of anonymity said Berman’s move was highly unusual, in part because in most cases, the government would continue to defend its actions following a conviction. They also noted that the DoJ had deemed it a priority to build up its convictions in such cases, in order to bolster its record on sanctions-related cases. Sadr was due to be sentenced in August, and could have faced a decades-long sentence on the charges for which he was convicted. The decision to seek to dismiss the case comes as the US government has separately launched a campaign to call for the release of an American-British dual national, Morad Tahbaz, from Iran. Tahbaz is a conservationist who was arrested in January 2018, and had been working on conservation causes with the United Nations Development Programme. Brian Hook, the US special representative for Iran, posted a video about Tahbaz on Twitter last week. Another