plead guilty (to something)
To formally admit and declare that one is guilty (of some crime or accusation). The defendant avoided a possible death sentence by pleading guilty to a lesser charge of manslaughter. My client pleads guilty, your honor.
plead guilty to something
to state that one is guilty of a crime before a court of law. Gerald refused to plead guilty to the crime and had to stand trial. Max pleaded guilty to the charge and then fled town.