Charles McGonigal, a former FBI agent who helped lead the investigation into Trump-Russia connections, is expected to plead guilty to charges of unlawfully working for a Russian oligarch.In an ironic turn of events, one of the individuals who worked tirelessly to take down former President Donald Trump by falsely accusing him of secretly collaborating with Russian officials and hackers was, in fact, the one engaging with influential Russians at the time.McGonigal, 54, a former top FBI counterintelligence agent based in New York, was charged in January with money laundering and violating United States sanctions by working for a Russian oligarch...