The Houston Democrat is a member of the House Judiciary Committee.
Mukasey told her that he would have the department check to see if his office had jurisdiction to investigate.
Rosenthal has come under fire since pornographic, racist and political messages in the Republican's e-mail account surfaced last month. The messages also included love notes between the married prosecutor and his secretary.
Rosenthal acknowledged in federal court last week that he made erroneous statements in a deposition about his deletion of office e-mails. A federal judge has indefinitely postponed proceedings about whether Rosenthal should be punished for deleting what appeared to be evidence requested in a federal lawsuit against the county.
