CorrectionsOne has a good article on how correctional employees can recognize and get help for co-workers suffering from PTSD before tragic consequences such as suicide occur.  

The site publishes a sit-down interview with Ellen Kirschman, who has worked as a police and public safety psychologist for over 30 years.

Take a look:

Q: What does PTSD look like for someone who has faced trauma on the job? Are there levels to how it can affect someone?

Ellen Kirschman: Post-traumatic stress disorder is a painful emotional condition lasting thirty or more days that develops in some first responders following exposure to:

1) A single extremely disturbing event such as combat, crime, an accident, or a natural disaster.

2) A series of such events. The psychological disturbance created by this exposure is so great that it significantly disturbs or impairs a person’s social interactions, ability to work, or to function in general.

The diagnostic criteria for PTSD must include a clearly identified trigger such as the threat of death, serious injury, or sexual violation. This is in contrast to other stress-induced conditions like cumulative stress or critical incident stress. Cumulative stress is a buildup of what might be called micro-insults.