Trump Indictments, page-126

Presidents retain their title after leaving office btw

It's a title, and nothing more. It confers absolutely no immunity from indictment, investigation or prosecution.

Depends on whether resigned after impeachment, the nature of the indictment etc.

Here's a freebie for you:

Someone is either a President, or a private citizen. A President cannot be charged with a crime- and that is the official stance of the Office of Legal Counsel, and that is that.