I was wondering if he may be onto a good thing here with regards recompense for his story, book deal, TV appearances etc.
I personally would hope he doesn't gain from this.
As you can't profit directly from a crime (otherwise we'd have had 'Reggie: his biography by Ronnie' at some point, no doubt) producing 'Dan James: Licenced to Walt', even if he gets 100 hrs community service, suspended for 3 years, would be a no-no.
There is a grey area - if an author decided that a book about James would sell, then he/she might pay James for participating in interviews. This happened when Gita Sereny paid Mary Bell for interviews. However, since the book Sereny wrote was, IIRC, more of an account of how Mary Bell turned into a child murderer and how social services missed the fact that she'd become a strange, disturbed child likely to do harm to others, rather than an account of the crimes themselves, it was hard to make the case that Bell was benefitting directly from her crimes.
In this case, though, I imagine that any attempt by an author to go into what James did would be problematic -given the national security angle.
Therefore, it would seem that the book and film deal will have to go on permanent hold...
Flying Lawyer or Pr00ne will, of course, be able to give the exact answer.