It very much depends on the specific crime he's been accused of. Lawyers specialize, and many get really specific. If you know any lawyers at all, ask them for a referral--they usually know who's the best for a particular specialty.
If that's not possible, contact the Michigan State Appellate Defender Office (http://www.sado.org/attorney.htm ), which has lots of resources, including a long list of criminal defense attorneys.
BTW, Geoffrey Fieger is probably the most famous attorney in Michigan, and certainly very good. But he is probably a better bet if you want to sue someone, not if you're facing criminal charges. His firm will also be CRAZY expensive b/c you will definitely pay for the brand name.
You'll have to check your state government website for information and search for harassement and email harrassment.
Now according to TV courts, which are not 'real' like your county courts, emails are read by a judge and considered.
I hate to say this but you are going to have to take legal action, and SAVE all these emails, and good luck because you are going to have to 'trust' a lawyer....yucch.
This sounds so serious though that you have to let someone in authority 'know' and I don't know if police will do anything...except the death threats and sexual threats they might arrest the person. Than you can get a court appointed attorney.