ALBANY – A political investigation shrouded in mystery reached the Court of Appeals Tuesday in a case that could determine if the judiciary can second-guess a district attorney’s decision to step aside from a particular matter.

The case involves the Working Families Party, an investigation of a city council election launched by Staten Island District Attorney Daniel Donovan, the prosecutor’s ex parte application to be relieved of the case, and a judge’s decision to grant the motion and appoint a special prosecutor without revealing why.