This is probably part of a plea agreement or non-prosecution agreement with a federal prosecutor.
That was my hunch, too, except I'm having a bit of trouble understanding how anyone in Washington, D.C. could authorize investigating a representative of the Chicago way. Aren't felonies normally swept under rugs?
As it is, Jackson and his wife seem to be getting off easy. In most such cases of a federal public corruption plea agreement, the feds insist on a publicized arrest, then a written plea agreement and allocution in open court that detail the crimes charged or that could be charged.