Glaring issue
I won't call it a plot hole, but if Roy was so smart and cunning couldn't he have come up with a much better plan than pretending to be an alternate personality for so long as risking his freedom/life. It seems like a really bad plan to rely on not getting stuck with a public defender - a much more likely scenario - and depending on very specific actions on the part of both your defender and prosecutor, not to mention the amazing risk you're taking altogether.
It made for a pretty good plot twist, but as plans go it doesn't really stand up to scrutiny.