Guilty But Mentally Ill

Hello. I need assistance to create a case analysis of a simulated GBMI case detailed below:

In a high-profile local case, a defendant has pleaded Guilty but Mentally Ill (GBMI.) Dina F. has been charged with first-degree murder. She is a 35-year-old woman who killed her 6-year-old son by drowning him in the family swimming pool. By all accounts, Dina had been extremely sad and listless for at least the past 8 months, after suffering a miscarriage in her 7th month of pregnancy. After the miscarriage, family members described Dina as losing energy, so that she rarely left the house and slept through much of the day. Dina lost weight and told her mother repeatedly that she felt as though she deserved for bad things to happen to her. Eventually, Dina began to go for days without bathing or brushing her hair, and did not seem interested in caring for her young son. Her husband noticed these changes, but kept insisting that she would snap out of it and get better. He ignored the warnings of family members that Dina should get psychological help.

One day, neighbors heard the sound of splashing in Dina's pool and her son's cries for help, and called the police, but the police arrived too late to save the son. Dina immediately told the police that she had killed the boy. She stated to police and to a psychiatrist that angels had been visiting her for months, and had warned her that evil forces were coming for her and her son. Dina said that she didn't really want to kill her son, because she knew killing was a sin, but that the angels told her that the only way to save her son's soul from evil would be by killing him. Dr. Green mentioned to you that she thinks that Dina could be diagnosed with Major Depression with Psychosis.

A reporter from the local paper is interested in learning more about the insanity defense and asks you for some background information. You send him a brief memo, outlining the following information regarding the insanity defense:

---Explain the elements of a "guilty but mentally ill" (GBMI) plea.
---Describe one of the legal standards used to determine whether a person is "not guilty by reason of insanity" (e.g., M'Naghten, Durham, American Law Institute).
---What are the repercussions for a defendant who is found "not guilty by reason of insanity" as opposed to a defendant who is GBMI?
---Do you think that Dina suffered from a mental illness, such as Major Depression with Psychosis (refer to DSM-IV criteria to support your conclusion)?
---Do you think that the GBMI plea is appropriate for Dina?