Witnessing the death of a law enforcement officer or viewing the body at the scene, especially when the victim was a friend or partner. Trauma is often increased if the officer believed he or she should have protected the person who died, or if the dead officer was temporarily serving in place of the officer. When an officer imagines him or herself as the dead officer, then visualizes the impact that their death would have on those they love, the traumatic impact of this event is greater.

A reasonable belief that death or critical injury was imminent and certain.

An officer accidentally kills or wounds a bystander, especially if the victim is a child.

An officer fails to stop a perpetrator from injuring or killing someone after the initial encounter.

Killing or wounding a child or teenager, even if the life of the officer was threatened by the person injured or killed.

Viewing the body of a child victim, particularly if the officer has children and even more so if the officer’s child is the same age and sex of the victim or if the child victim is similar in some other way to the officer’s child, such as appearance, clothing, toys, or school. The impact of this experience is often increased if the body has deteriorated, if the child was tortured and/or if the officer hears a graphic confession from the murderer, especially when pain was intentionally inflicted on the child.

When a dead victim becomes personalized, rather than just an unknown body, through interaction with grieving family members or friends, or from information gained in numerous ways from the scene, news reports, search warrants, and so on. Continued association with the pain of survivors through an investigation and trial (and often long after) also can personalize the dead victims.

The terror of being caught in a violent riot. Trauma may be increased when children are present in the crowd and the officer cannot use deadly force to defend him or herself for fear of hurting the children.

An officer is blamed or told he or she is responsible for the death of an innocent bystander, law enforcement officer or a child victim by his or her department, family members of the victim, or the media. Guilt, such as feeling responsible for violence or death, whether irrational or based on fact, usually intensifies symptoms of PTSD. Events such as exchanging shifts with another officer who is killed while working the exchanged shift or responding to a call minutes after an officer is killed can intensify symptoms of PTSD when the officer blames him or herself for the event. ("It’s my fault he/she is dead; I should not have taken sick leave." or "If I had been there, he would not have gotten killed.")

Particularly bloody or gruesome scenes. Horror of the crime and/or the suffering of the victims. Length of exposure to crime or accident scenes that involve decaying and dismembered bodies, especially when children are victims.

Observing an event involving violence or murder, but not being able to intervene (i.e., "I watched him kill her. She was screaming for my help but there was nothing I could do.")

Feeling responsible for someone’s life (i.e., a crisis or hostage negotiator, attempting to resolve a potentially lethal situation, especially if the event drags on for hours). Symptoms may occur even when victims are rescued as a result of stress hormones released during long negotiations.

An undercover assignment in which the officer is constantly "on-guard" because of the likelihood of being hurt, killed, or discovered. This is particularly a problem if the officer grew up in a family where he or she had to always be "on-guard" against physical, emotional, or sexual abuse, because the undercover experience mirrors the fear of the childhood experience.

When an "informant" or "asset" developed by an officer is murdered for providing information to law enforcement.

When suspects who have been indicted, are being tried, or are incarcerated threaten the officer and/or the officer’s family with violence and are deemed capable of carrying out these threats.

Inappropriate response of management to an officer’s involvement in any of the above critical incidents can significantly increase their traumatic impact.

Being referred to as a "Hero" after being involved in an incident where other officers died or were critically wounded. Being labeled a hero when fellow officers died at the scene can dramatically increase feelings of guilt and PTSD symptoms.