Jackson Jr.’s future legal battle

Jesse Jackson Jr.'s letter of resignation included for the first time his own acknowledgement of the worlds worst kept secret--that he's facing a federal investigation.

The letter also reveals that he is cooperating in that investigation, and possibly trying to get his wife Sandi off the hook.

"I've never seen it in a written plea agreement that a deft would admit or agree to step down from public office, that he holds, I've never seen that. Now, it's been understood," says veteran defense attorney Mike Monico.

Monico, who handled the delicate negotiations leading to the guilty plea from former Chicago Alderman Ed Vrdolyak, says you'll never see it in writing, but prosecutors probably insisted that Jesse Jackson Jr.'s resignation had to be part of any plea deal.

Monico explains that Jackson saying he's willing to, "accept responsibility for my mistakes" is language specifically tailored to pleading guilty and possibly getting a shorter sentence.

"That expression, ‘accept responsibility,' is key language as part of any kind of plea agreement because the defendant wants to make certain that he is accepting responsibility, and the judge, and wherever he's gong to be sentenced for his conduct, I'll be certain that its an important part of the plea," Monico explains.

Jackson is under investigation for allegedly spending campaign funds to redecorate his home. His wife Sandi is a part of the investigation but is not a target. Monico says another revealing phrase in that letter is where Jackson takes all of the blame for the conduct under investigation.

"That is interesting that he says that these are my mistakes and my mistakes alone," says Monico. "And so I'm thinking, that is a benefit to his wife to say that."

Monico says if Jackson pleads guilty to the allegations that have been reported so far, it's likely he would get less than a year in prison.