NEW YORK — Former chief of the FBI’s New York City counterintelligence division Charlie McGonigal pleaded guilty in Manhattan Tuesday to helping a sanctioned Russian oligarch find dirt on his enemies after his retirement. The former special agent in charge, who retired from the FBI in 2018 after a two-decade career that included Russian foreign counterintelligence work and investigating oligarchs, was arrested in January on charges in New York and Washington, D.C., alleging he worked for Russian President Vladimir Putin associate and aluminum tycoon Oleg Deripaska after his retirement. The fed...