House Judiciary Committee Subpoenas Abu Gonzales

New York Times:

The House Judiciary Committee demanded more documents today from Attorney General Alberto R. Gonzales in the panel’s inquiry into the dismissals of eight United States attorneys.

The committee’s chairman, Representative John Conyers, wrote Mr. Gonzales that the documents were being subpoenaed because the Justice Department’s cooperation so far in turning over documents “falls far short of what is needed.”

Mr. Conyers, a Michigan Democrat, said he appreciated Mr. Gonzales’s cooperation in supplying some documents to the committee’s subcommittee on commercial and administrative law. Still, Mr. Conyers said, the department has not responded fully despite weeks of negotiations with the subcommittee.

Why are they not cooperating? What are they hiding?