Give her a lie detector test.
The results of that would be highly dependent upon which of her many type of liar is dominate at the time. Psychopathic Liar, Congenital liar, Damnable liar, bald faced liar, Sociopathic liar, Compulsive liar, Chronic liar, Habitual liar, etc. or all of the above.
The damn thing would probably short circuit and blow a fuse if she told the truth
They tried that once...