Because this needs to be done 1000% right, there is no margin for error, everything has to be done in an iron clad manner that cannot be dismantled by half-assing it. Indicting a former president is a first in the history of this country, and this former president is nothing short of a cult leader with millions of unshakable followers, many of whom are armed to the teeth and ready to burn this country to the ground for him. So this has to be done very friggin carefully.