Order that Petraeus testify before Congress, regardless if he resigned from his post!

General Petraeus should be REQUIRED to testify before Congress. Regardless if an official resigns from office, if they are scheduled to testify before ANY court or Congress, they should be required to appear by law. Their knowledge, memory of the facts, or involvement in whatever they are being called to testify before should not be vacated because they resign from any office.