Why would they have offered him ANY deal? (Do we know they did?) All the co-conspirators agreed to testify, and it was a slam dunk case. He could have plead guilty of his own conscience, of course, but no reason for the prosecution to offer any incentives in this case.
It actually seems that they did not. The only reason would be to spare the expense of a trial, which isn’t much in the grand scheme of things in this particular instance. They can probably extract money from him in fines, presumably he has some left somewhere.
