How do you think our justice system should deal with mentally ill offenders?

This is an opinion question, and may have multiple differing answers that are all correct, but I'm going to try my best to answer it.

I think the justice system should declare mentally ill offenders not guilty, even if they are guilty of the crime, if their mental illness may have played a part in the offense. However, if there are mentally ill offenders whose mental illness had not played a part in the offense, they may be found guilty, but while sentencing them, the justice system must still take their illness into consideration.