The fact the former DA who "promised" not to charge Bill Cosby criminally after he had to admit in a deposition in a civil claim that he had, indeed, raped Andrea Constand in her suit against him makes Cosby look even worse. This sociopath wanted special treatment. There was NO way in HELL ANY DA can make a promise like that. Besides, there was no WRITTEN, FORMAL agreement not to press charges.
Any DA making promises like that is doing something highly improper. Yes, it should be investigated.
Cosby was not and is not immune from prosecution for things he said in a civil suit. There are NO fifth amendment protections when you are sued.
He make walk free anyway.
God, what a sociopath.