Welcome to Fluther.
If you’re writing from your own situation, then I’m sorry for what you all must be going through. If you’re writing for a story plot line, then that would be good to know…
If the suicide is obvious, such as when the person has been talking about it and making clear plans for departure: giving away assets, updating or making a will, saying goodbyes to people, etc., and there is no clear evidence of participation by anyone else, then there should not be prosecution, no matter the circumstances, as long as there are no other witnesses or “parties to” the suicide who could have prevented it.
Where it gets tricky is if a person is disabled, for example, and would clearly need assistance to commit the act. So “method” has to be considered and must be one that the person could clearly perform unaided—including without “prior aid”, such as in obtaining or preparing lethal quantities of drugs, for example, that the person could not get without assistance.
But before considering it – even though I think the person surely has the right to do it – if it’s being done for “acute” medical reasons, that means that those reasons may be resolved in time. After all, an ‘acute’ medical condition is not chronic and generally not long-lasting.