The Potential Predatory Violence Inventory (PPVI), is an inventory that can be used as screening in the detection of risks of extreme violence behaviors, for example school shootings. It was recently published in

Penagos-Corzo, J. C., Antonio, A. A., Dorantes-Argándar, G., & Alcázar-Olán, R. J. (2019). Psychometric Properties and Development of a Scale Designed to Evaluate the Potential of Predatory Violent Behavior. Frontiers in Psychology, 10(1648), 1-10. doi: 10.3389/fpsyg.2019.01648

https://www.frontiersin.org/articles/10.3389/fpsyg.2019.01648/full

The PPVI consists of 13 items. Confirmatory factor analysis indicates that it is an instrument with an excellent fit to the theoretical model.
The PPVI evaluates four factors of predatory violence:

• Anger contained,
  Taste for weapons,
  Suicidal ideation,
  Take justice into your own hands.

The scientific article with the published version is in: Frontiers in Psychology

You can download from here:

The inventory (PPVI) in Spanish, with profile sheet/standards and a minimum guide [PPVI-13-es.pdf]
The inventory (PPVI) in English, with profile sheet/norms and a minimum guide [PPVI-13-en.pdf]
The inventory (PPVI) in Spanish, with profile sheet/standards in a semi-automatic version in Excel [PPVI-13-es.xlsx]
The inventory (PPVI) in English, with profile sheet/norms in a semi-automatic version in Excel [PPVI-13-en.xlsx]