What is Kenneth Blackwell's Obligation to Answer Rep. Conyers' Questions?

I'm asking this question because I don't know the legal answer, and I think it's a very important question to consider.

In Congressman John Conyers' House Judiciary Committee Democratic Staff report, entitled "Preserving Democracy: What Went Wrong in Ohio", numerous irregularities involving the 2004 Ohio Presidential Election (pre-election, during the election, and post-election) are identified and discussed. Most DUers, and perhaps most Americans who are aware of the report, believe that the allegations contained in it are serious and cast considerable doubt on the integrity of the Ohio election. Yet, Kenneth Blackwell, the Ohio Secretary of State who was responsible for the running of the election, has refused to answer any of the many questions posed to him by Conyers' Committee.

Recently, in response to a thread that I posted that involves the integrity of the Ohio election, another DUer (who I won't identify because this was a private conversation - but I can tell you that he wasn't a friend of mine) told me that Blackwell was correct not to answer the Conyers Committee's questions because Conyers has no legal jurisdiction in the matter. I didn't know how to answer him because I don't have sufficient legal background.

I would be very interested to know what others think of this.

Because explanations would be more useful for learning how to argue this issue.

Committee. Conyers had no subpoena power and could not put anyone under oath. His meetings, so I understood, could not even be called "hearings" since that would suggest an authority Conyers did not have. The Republican run House Judiciary Committee made sure that Conyers' efforts would be marginalized and given no official designation, recognition or support.

Consequently Blackwell could blow him off with impunity. There was no legal requirement that he respond or cooperate with Conyers. As for "ethically" well obviously Blackwell is a stranger to the concept of ethical behavior. Naturally Blackwell wouldn't give Conyers' investigation the time of day and there was nothing Conyers could do about that.