What are the Shariah rulings applicable to a homeowner who killed a thief who broke into his home with the intention of theft and rape, and was armed with a deadly weapon?

Scholars refer to an aggressor against life, property, or honor as a 'sa'il' (assailant). Repelling the assailant is permissible by whatever means effective, and it must be done with the lightest possible means, then the next lightest. Thus, it is not permissible to kill him if he can be repelled by a lesser means. However, if he cannot be repelled except by killing, then killing him is permissible, and there is no sin upon the killer nor any liability.