Special Counsel Robert Mueller may have considered Mike Pence a marginal figure in the events at the heart of his Russia investigation. Or he simply decided that trying to question the vice president would cause more trouble than it was worth.

Those are among the theories posed by legal experts, including a former federal prosecutor and a onetime government lawyer, on why Mueller never asked for an interview with Pence, whose name appears a handful of times in a 448-page report on the investigation that has consumed most of President Trump’s first term.