One of the things asked of General David Petraeus will be how classified documents may have ended up on the computer of his mistress, Paula Broadwell.
Petraeus had been reluctant to testify following his resignation as CIA chief, but pressure had been growing in Congress for him to appear.
The former general has agreed, sources told ABC News, to testify on Thursday.
A source familiar with the case also told ABC News that Broadwell admitted to the FBI she took documents from secure government buildings. The government demanded that they all be given back, and when federal agents descended on her North Carolina home on Monday night it was a pre-arranged meeting.