Interesting area of research. I want to learn from you about forensic psychiatry (understanding the mind and behaviour). Hope you could give me any reference articles to understand this theory.
the answer to your question will depend on what the forensic issue is. Capacity to stand trial, insanity, capacity to write a will, capacity to conduct ones own affairs without a guardian being appointed, etc. One must ask the attorney what issue they would like you to write a report for or what issue you are being asked to testify on..
It depends on what you mean by "cognitive interview". If by "cognitive interview" you mean an assessment of an accused person's ability to think clearly, understand issues, and form intent, I would say that a cognitive interview is not only useful for forensic examination purposes, it is essential.
I would point to conscious information (which the interviewee controls/regulates consciously) and pre-conscious information (of which the interviewee is unaware). If the interview elicits only the former, i think it will be of little use. If it elicits both, they can be compared. In forensic cases, evaluated with the DMM-AAI (Adult Attachment Interview interpreted with the DMM method), the two forms of information are highly discrepant. The person can say the right thing, but their actions are different. There are full discussions in Assessing Attachment in Adulthood and Raising Parents. The introduction to the attached paper might be helpful, even though the topic is PTSD, not forensics.