Gosh, this is a tough one. What concerns me about this situation is that it appears Cesco didn't give you any warning before biting. Usually dogs will give a warning growl and snap before biting, especially if it involves their own pack members, i.e. the family.
My white Dane is wired incorrectly, and he is an aggressive (fear-aggression) dog. I am aware of this, and I make sure that he is never in a position to feel uncomfortable with a situation. When people come to the house, he gets baby-gated in the dog room where he can see what is going on. IF he knows the people, once things have calmed down he can come out and socialize. If he doesn't, he stays in that room until the people leave. At the vet, we only see women, men frighten him, and they are usually aware of the situation and are willing to work VERY slowly with Mickey to earn his trust. I still muzzle him while drawing blood or giving shots just to be safe.
I can tell you though, never once has he bit me, my husband or our other dane. It never even occured to me to be afraid of him that he might bite me. I am alpha and he knows it. Cesco is obviously under the impression he is in charge, mixed with the propensity for vicious behavior you have a VERY dangerous situation on your hands.
Please start by hiring a behaviorist and have her/him come to your house to observe. They certainly can help you understand what may be going through Cesco's head. Also, PLEASE don't allow Cesco access to anyone outside of your family that lives in your house. If he bites, you will be stuck with an administrative and legal mess on your hands, and knowing the dog's history you're at risk for having him PTS.
There are some dogs that for whatever reason are just wrong in the head, and there is nothing you can do to "fix" them. This isn't your fault, it just is what it is.