In the case of a person like you talk about, disfellowshipping is a must. And so should calling the police.
At risk of being shot down, i will state my thoughts on disfellowshipping.
Here goes...
I have no problem with the practice in itself. Maybe i see it wrong but please here me out. I will use the example of a club for a particular brand of motor vehicle.
Neville buys a corvette and off he goes and also joins the local corvette club. The rules of the club state that to be a member, you must own at least one corvette. Some time later, Neville sells his corvette and buys a datsun. When it is found out, the club terminates his membership. No real problem though. His friends who have corvettes still talk to him and invite him to dinner, although they do tease him a bit about the car and hope he will buy another corvette one day...Neville just might.
The problem is the labelling and shunning. Now, lets assume the corvette club people will no longer even talk to Neville, some even cross the street to avoid him. Worse, he is labelled an Japotate for buying the Datsun. No longer can he have dinners with his friends, nor the company of his brother, a rabid corvette owner. The club and his brother hope that by shunning him, he will see the error in his choice of car and buy another corvette. Unfortunatley, neville is broke and could never afford to buy another corvette. Heartbroken he hangs himself.
Disfellowshipping can and should be used i feel by a religion for those who break the rules. You are OUT. No longer a member of the 'club'. Some times it is to remove an evil person. Sometimes to delete membership of somebody who no longer wants 'in'. The problem is in the shunning. Should the ex JW be treated just the same as any other person or loved one, disfellowshipping would be seen as a no big dead for most. "Oh, yeah, cousin Frank does not believe anymore, big deal, thats his choice, he's a great guy, we see him often and just dont talk religion because we never can agree!" or in the case of the scumbag, people would be justified in avoiding him and calling the police etc
Tell me nicely if you think i am wrong! Again, i see the shunning, labelling and underlying information control as the problem rather than the actual being removed, disfellowshipped, from the congregation.
Oz