"Aside from the political *** for tat that will be bound to happen if former presidents are paraded through the courts, it can be argued that, like cops, judges and prosecuters, presidents and officers of the United States have immunity for actions taken during the performance of their duties. And if they do not it will take years for the courts to settle the question, further destroying the public's faith in their governing institutions."

While there is no precedent for criminal prosecution of a sitting president, it has long been, and continues to be, a subject of debate and discussion. However, there is a lengthy history of prosecutions against corrupt officials while in office. An honest assessment easily concludes that both sides of the political duopoly are progressively losing faith in government. 

"The time to nip the problem is while the president and officers are available for impeachment."

Ideally, yes. Realistically, the public believes that approach hasn't worked.