Knives can do terrible damage to human flesh, and anyone who has used a knife as a weapon in the past and is now under similar psychosocial stressors or circumstances is a candidate to commit violence. Again, past violent conduct is the single best predictor of future violence.
Just as the question, "Have you ever had trouble with the law," can be quite useful in obtaining important personal history, it is also useful to ask, "What is the most violent thing you have ever done?" This can be contrasted with "What is the most violent fantasy you have ever had?"
The personal interview can be supplemented by collateral interviews with a close relative or friend of the patient and can produce invaluable information. The forensic psychiatrist regularly obtains all kinds of records with collateral information from prior hospitalizations, jobs, mental health treatment, the military or school. The office clinician may not find it appropriate to ask for most of these, but, with the patient's permission, can almost always request and receive information from other doctors and mental health care professionals who have seen the patient in the past.Standardized Instruments
Clinicians who are asked to assess the risk of violence or dangerous behavior are increasingly supplementing their clinical assessments with the use of standardized risk assessment instruments. There are a number of these, including:
- The Hare Psychopathy Checklist-Revised (PCL-R), and its Screening Version (PCL-SV). This test is a clinical construct rating scale that measures attributes of people considered at high risk for crime or violence.
- The Violence Risk Appraisal Guide (VRAG), an actuarial risk assessment instrument that includes 12 variables covering childhood history, adult criminal history, demographics and psychiatric diagnosis. The most weight is given to the psychopathology variable, as defined by the PCL-R.
- HCR-20 (Historical, Clinical and Risk Management). This risk assessment tool combines historical risk factors with clinical judgment regarding dangerousness. Its 20 items cover historical, clinical and risk management issues.