Well, "mis-charged" would mean making the wrong charges. The lawyer interviewed used "over-charged" and sort of explained he meant that the charges laid were the most serious charges that could be brought, e.g. Murder 1, instead of manslaughter, concealing a dead body, etc.
Hey, it's not *my* term. It is apparently not unique to this lawyer:
To file a criminal complaint for more serious crimes than the known facts support, most often to intimidate the accused into accepting a plea bargain.
That definition is from one of several online legal dictionaries (legal-dictionary.thefreedictionary.com/over-charge) where I found it. It was actually apparently first used to refer to this case by CA's defense years ago, according to the quick google I just did