I suggest you get a lawyer involved in this matter. There are a couple of things that can be done to obtain the domain. Some have already been mentioned in this thread. A couple of other suggestions are to trademark the model's name, which will provide you with the legal action to obtain the domain.
Another way is to get a registrar, like Moniker as a third party involved, so you can buy the domain. They may be able to help you, as they have the connections to other registrars.
Good luck!
Purple Haze