[QUOTE=pabrown;174905]My problem is the main character is a sociopath. His goals are anathema to everyone else around him. Clearly no one can root for him, he's not sympathetic but I have to make him so fascinating readers will stick with the book. [H/QUOTE]
Pulling this off will take strong writing skills, which fortunately you have, from the little I've seen. And fortunately there are people who enjoy a villain protagonist.
In this case, I expect (and hope) that few if any of your readers will be rooting for this guy to succeed. They will be rooting for him to fail and waiting to see how it happens. You might consider building up one or more secondary characters who readers can root for in a more positive way. For example, could his new partner have a prominent role throughout the story, so it's sort of a battle between two characters? Could you do something like they did in Silence of the Lambs, where they showed the most recent kidnapped girl trying to survive?
This isn't the kind of book I read, so I don't know how other authors have handled it. I believe I've heard that in Gone Girl by Gillian Flynn, all the characters are unlikable, and it's been a bestseller (with the negative reviews generally being about characters' unlikeability). So it may be that you're on exactly the right track, and you just need to make it clear to readers that if they need a hero they can root for, this isn't their book.