Why is Mayawati afraid of a CBI enquiry ?

The recent murder of a goverment official by politicians in Uttar Pradesh is shocking. The Mayawati govermnent is suspected to be involved in the matter and various fractions have asked for a CBI enquiry to ensure a free and fair trial. I don't understand why Mayawati has rejected the need for a CBI enquiry. What is she trying to hide ? If she is innocent what is she afraid of ?

Her dismissal of a need for a CBI enquiry makes me suspicious. A CBI enquiry is the need of the hour to ensure justice is done.