Homicidality Scales: What Clinicians Need to Know About Measuring Homicidal Ideation

When a client tells you they're thinking about harming another person, you need to act — and you need to act well. In that moment, many clinicians do what I did early in my career: they search for a validated instrument. Something they can point to, score, and document. What they often find is a landscape that is considerably less organized than the parallel world of suicidality assessment — and that gap matters clinically.

The truth is that there is no single validated homicidality scale in the way the Columbia-Suicide Severity Rating Scale (C-SSRS) provides a consensus instrument for suicidal ideation (Posner et al., 2011). The clinical measurement of homicidal risk is distributed across several instrument families, and understanding what each can and cannot tell you is the foundation of a competent assessment.

The Instruments That Actually Exist

Several validated tools bear on what practitioners mean when they search for a homicidality scale.

Psychiatric rating scale hostility items: The PANSS Hostility Item (P7) and the BPRS Hostility subscale are among the most widely used clinical measures of aggressive intent in inpatient and outpatient psychiatric settings. They provide a quick, anchored severity rating — but they were designed for monitoring psychiatric symptoms in treatment contexts, not for structured violence risk assessment. A high hostility score tells you something meaningful about current state; it does not, by itself, tell you what someone will do.

The Overt Aggression Scale and its Modified Version (OAS-M): Developed by Yudofsky and colleagues (1986), the OAS-M rates the frequency and severity of verbal and physical aggression, as well as subjective feelings of aggression and the interventions required to manage them. It is useful for tracking change over time in inpatient settings. Like the psychiatric rating items, it describes behavior; it does not weigh the determinants of future harm.

Structured professional judgment tools: The HCR-20 (Webster et al., 1997; Douglas et al., 2013) and its successors represent the most rigorous framework currently available for violence risk assessment. These tools organize assessment across historical risk factors, current clinical factors, and future risk management variables. The SAVRY (Borum, Bartel, & Forth, 2006) applies the same structured professional judgment approach to youth.

These tools do not produce a number you look up in a normative table. That architecture is deliberate: the research is clear that actuarial scores alone perform less well than structured professional judgment for targeted violence specifically (Monahan et al., 2001).

These tools produce a structured summary of risk and protective factors. However, these tools do not produce normative data based on community and clinical samples from teachers and parents. And, the protective factors are limited to only six items. Having normative data can significantly enhance the Structured Professional Judgment process as it relates to both risk and protective factors.

Where the Evidence Is Strongest — and Where It Thins

The MacArthur Violence Risk Assessment Study (Monahan et al., 2001) remains one of the largest and most rigorous examinations of violence prediction in clinical populations. Its central finding deserves careful attention: violence risk is not a fixed trait you measure once. It is a dynamic, contingent phenomenon. The strongest predictors interact with context — access to means, substance use, recent stressors, the quality of relationships.

That finding shapes how I practice. A scale score is a moment-in-time measurement. A client's risk on Monday, following a confrontation with a family member and access to a firearm, is genuinely different from their risk on Friday, after a productive therapeutic session and reconnection with a support system. The instrument does not update itself. Clinical judgment has to.

What a Competent Homicidal Ideation Assessment Actually Covers

When I assess a client who has disclosed homicidal ideation, I organize the interview around several domains, regardless of which formal instrument I am documenting alongside it.

Ideation characteristics: Is the ideation passive ("I wish something bad would happen to them") or active ("I have been thinking about how to do it")? Passive ideation in the context of frustration carries different clinical weight than an elaborated fantasy with a specific target, timeframe, and method.

Intent and planning: Has the client made any concrete moves toward acting? Have they acquired means, researched methods, or scouted a location? The gap between ideation and intent narrows quickly when planning behaviors emerge.

Access to means: Lethal means access is one of the most modifiable risk factors in any violence risk assessment. It is also one of the most consistently underassessed. I ask about it directly and counsel on means restriction when risk is elevated.

Target identification: Is there a specific person? A specific grievance? Fixation on a named target is one of the most robust warning signals in the research literature. The degree to which the target occupies the client's mental life — and the depth of perceived grievance — carries significant clinical weight.

Protective factors: What is keeping this person from acting? Connection to others, real and anticipated consequences, stated values, investment in the future — these matter as much as the risk factors, and they are what intervention has the most leverage on.

No scale replaces the clinician. The value of validated instruments in this domain is that they organize your inquiry and support consistent documentation. They do not do the assessment. You do.

The Suicidality Parallel — and Where It Breaks Down

Clinicians with strong suicidality training often apply similar interview frameworks to homicidal ideation, and that transfer is reasonable up to a point. The research on targeted violence, however, points to a pattern that does not map cleanly onto the suicidality literature.

The concept of "leakage" — the tendency of prospective attackers to communicate their intent to someone before acting — is more consistent in targeted violence cases than in most suicidal crises (Fein & Vossekuil, 1999). The U.S. Secret Service's National Threat Assessment Center has consistently documented that targeted attackers show observable warning behaviors in the period before violence, and that most communicate intent in some form beforehand (NTAC, 2021).

That distinction has clinical implications. A client who is suicidal and a client who is homicidal may both be in acute crisis, but the professional referral pathways, the duty-to-warn considerations, and the intervention strategies differ in ways that matter. A homicidal ideation assessment should be followed by a structured threat assessment framework, not only a suicide protocol.

Practical Guidance

For clinicians building competence in homicidal ideation assessment, I would offer the following.

Learn the structured professional judgment literature. The HCR-20V3 user guide is rigorous but accessible. It will give you a professional vocabulary for this assessment domain and a framework you can defend in clinical documentation.

Assess means access every time, without exception. Counsel on means restriction when risk is elevated. This is the most modifiable factor in the picture and the one clinicians most often skip.

Document the clinical reasoning, not only the conclusion. A note that reads "denied intent to harm" does not demonstrate a competent assessment. The clinical record should show what you asked, what you found across the key domains, and why your professional judgment is what it is.

Know your duty-to-warn obligations under your jurisdiction's law and consult with colleagues when the picture is ambiguous. The Tarasoff framework has evolved differently across states, and the line between protected clinical information and a duty to protect a third party is not always clear from the statute alone.

References

Borum, R., Bartel, P., & Forth, A. (2006). Manual for the Structured Assessment of Violence Risk in Youth (SAVRY). Psychological Assessment Resources.

Douglas, K. S., Hart, S. D., Webster, C. D., & Belfrage, H. (2013). HCR-20V3: Assessing risk of violence — User guide. Mental Health, Law, and Policy Institute, Simon Fraser University.

Fein, R. A., & Vossekuil, B. (1999). Assassination in the United States: An operational study of recent assassins, attackers, and near-lethal approachers. Journal of Forensic Sciences, 44(2), 321–333.

Monahan, J., Steadman, H. J., Silver, E., Appelbaum, P. S., Robbins, P. C., Mulvey, E. P., Roth, L. H., Grisso, T., & Banks, S. (2001). Rethinking risk assessment: The MacArthur Study of Mental Disorder and Violence. Oxford University Press.

National Threat Assessment Center. (2021). Averting targeted school violence: A U.S. Secret Service analysis of plots against schools. U.S. Secret Service, Department of Homeland Security.

Posner, K., Brown, G. K., Stanley, B., Brent, D. A., Yershova, K. V., Oquendo, M. A., Currier, G. W., Melvin, G. A., Greenhill, L., Shen, S., & Mann, J. J. (2011). The Columbia–Suicide Severity Rating Scale: Initial validity and internal consistency findings from three multisite studies with adolescents and adults. American Journal of Psychiatry, 168(12), 1266–1277.

Webster, C. D., Douglas, K. S., Eaves, D., & Hart, S. D. (1997). HCR-20: Assessing risk for violence (Version 2). Mental Health, Law, and Policy Institute, Simon Fraser University.

Yudofsky, S. C., Silver, J. M., Jackson, W., Endicott, J., & Williams, D. (1986). The Overt Aggression Scale for the objective rating of verbal and physical aggression. American Journal of Psychiatry, 143(1), 35–39.