The case for obstruction of justice involving efforts to impede the Mueller investigation is far stronger, based on publicly known evidence, than our public discussion would suggest.

…It is now reported that Manafort was essentially double-dealing against Mueller and his investigators, with his lawyers allegedly reporting confidential information to Trump’s lawyers about his discussions with Mueller while he was supposedly cooperating with Mueller.

…Additionally, I would assert that while a president can lawfully pardon almost anyone, for almost any crime, a pardon could also be crucial evidence in support of an obstruction of justice case, and potentially an additional count in an obstruction of justice case.

If a pardon is offered to influence a witness in a criminal investigation, that pardon could indeed be a crime.

…Additionally, if Manafort is pardoned, he would almost immediately be required by Mueller to testify before a grand jury, under penalty of perjury, and would have to testify truthfully, or he would be indicted for new crimes of perjury that would not be covered by the pardon.

Manafort pardon would be impeachable, indictable and convictable | TheHill

hmmm