When a police officer is a hostagetaker, the hostage negotiator experiences additional stressors such as the perpetrator's knowledge of the tactics and objectives of negotiations and the special circumstance this brings to negotiating tactics and dynamics. Special weapons and tactical units have the added stressor of having to target a fellow officer, perhaps one whom they know personally. This increases reluctance to fire on the perpetrator. The mechanics of handling the situation may be impacted by either impatience in wanting to resolve the situation too quickly or a reluctance to use force even when circumstances warrant it. Regarding psychological effects, responding officers tend to become angered that a fellow officer would put them through the stress and danger of the incident. The perpetrator is under the stress of believing that his act will terminate his career and all support systems, making him vulnerable to suicidal thoughts. The perpetrator's family is under the pressure of having to deal with the community's reaction to the incident. Departments should debrief officers following the resolution of such incidents and develop a sound policy for responding to the perpetrator after the incident. Most importantly, departments should identify troubled officers and provide help for them before acting-out behavior occurs. A checklist for identifying such officers, 6 case histories and 1 reference.