Serious mental disorders can affect a person's culpability for a particular criminal offense by affecting that person's mental state at the time of the alleged commission of the offense. Additionally, a person's mental disorders can be severe enough that the person can be deemed incompetent to stand trial. In either instance, it is likely that a mental health expert would need to evaluate your husband to make such a determination. However, your husband should consult his attorney with the specific details of his case as well as his mental health issues and ask the attorney's advice about how to proceed.
Mr. Bell is correct in his answer. Keep in mind that if you don't hire an expert to give testimony of his "frame of mind" then you really don't have much concrete proof of his illness. While it may be obvious to you and the people around him, it may not rise to the level that a judge could agree with under the law. To protect your husband you need to contact an attorney who knows his way around mental health and how it works with criminal charges. Good Luck!
Call 615-736-9596 for consultation. This answer does not create an attorney-client relationship. This answer is for information only. Call me or another attorney to represent you.