Regarding on his case, manslaughter and armed robbery you said, did any of this involved a minor under age of 18? There's one major exception for a US citizen/ greencard holder to petition is due to 2006 Adam Walsh Act. If his crimes didn't involve any minor then disregard first part of my comment.
My next question is, when did you meet? Before he went to prison or while he's serving it?
Few assumptions might rise a few questions but what you really need to prove is the bona fide marriage. It's the intent and the actual relationship. These can be challenging to prove, since many limitations are involved. But that doesn't stop someone on marrying someone obviously.
I humbly think, in your case, look at it in different perspective. Build your case by asking what makes this not to pass? Then, provide strong evidences that will support bona fide relationship and intent to marry. Your husband's incarceration is his circumstances, but the immigration proceedings is your circumstances. You need to prove that above all, you are not coming in the States under false pretense of marriage and in good faith, just happen to be married to him.
I hope you find your "aha" moment. Best of luck. Kindly update us in the future.