You asked a hypothetical, so I will answer with hypotheticals:
The prosecutors hold most of the cards. He has you in jail. He has confiscated all your property and has your wife and children in jail.
He claims that he has witnesses who will perjure themselves and lie to prove his case.
He offers to cut a deal so that he can get a quick conviction, and you can stay out of jail.
He doesn't put anything in writing, but insists that you do.
Four words:
I need my lawyer
Easier said than done in that situation though.
If he is as innocent as he claims it must have felt like he stepped into the Twilight Zone. Like he woke up in an itty bitty teensy weensy Chicago on the border. And don't forget that the conspirator's customers were the drug cartels.
Seriously! ... HELP, MR. WIZARD!!!!!