Equality before the law is an important principle. If any monarch did committ a crime e.g. by assualting someone or damaging wildlife they should be subject to the same proceures as anyone else.
1. Civil and criminal proceedings cannot be taken against the Sovereign as a person under UK law.
2. Acts of Parliament do not apply to The Queen in her personal capacity unless they are expressly stated to do so.
I suggest making the Queen subject to the law in the same way as everyone else.