Why would a Commonwealth Attorney be assigned to a case if the charges are for a class 1 misdemeanor?

Answer 1

It depends on who has the title "commonwealth attorney" -- if that's the same as the "district attorney" in many states, then that's the proper office to bring charges in a state criminal matter.

If you mean the head of the department -- rather than a deputy of staff attorney within the office -- then it would have to be because of political considerations.