Low level of threat: A threat that poses a minimal risk to the victim and public safety.
• The threat is vague and indirect.
• Information contained within the threat is inconsistent, implausible, or lacks detail.
• The threat lacks realism.
• Content of the threat suggests the threatener is unlikely to carry it out.
Medium level of threat: A threat that could be carried out, although it might not appear entirely realistic.
• The threat is more direct and more concrete than a low-level threat.
• Wording in the threat suggests the threatener has given some thought to how the act will be carried out.
• There may be a general indication of a possible place and time (though short of a detailed plan).
• There is no strong indication that the threatener has taken preparatory steps, although there might be some veiled reference or ambiguous or inconclusive evidence pointing to this possibilityan allusion to a book or movie that shows the planning of a violent act, or a vague, general statement about the availability of weapons.
• There might be a specific statement seeking to convey that the threat is not empty: “I’m serious!” or “I really mean this!”
High level of threat: A threat that appears to pose an imminent and serious danger to the safety of others.
• The threat is direct, specific, and plausible.
• The threat suggests concrete steps have been taken toward carrying it outfor example, statements indicating that the threatener has acquired or practiced with a weapon or has the victim under surveillance.
Source: “The School Shooter: A Threat Assessment Perspective,” a report issued by the Federal Bureau of Investigation http://www.fbi.gov/publications/school/school2.pdf