"The Federal Bureau of Investigation keeps track of instances of "justifiable homicide," which it defines as "the killing of a felon by a law-enforcement officer in the line of duty," but it doesn't note which of those involve mental illness. While crime rates nationally have fallen almost every year since the late 1990s, justifiable homicides by police officers have risen, from 297 in 2000 to 410 in 2012.
Hidden within that category is what is known informally as "suicide by cop," when a person intentionally provokes an officer into using lethal force. Chuck Wexler, executive director of the Police Executive Research Forum, in Washington, D.C., which researches law-enforcement issues, said he believes this type of suicide is increasing in frequency.
Jill Harkavy-Friedman, senior director of research at the American Foundation for Suicide Prevention, said there aren't many studies of suicides that involve law-enforcement officers. A small number of studies, based on police records, have found in at least half the cases the victim had a known psychiatric history, and in at least a fifth the victim was undergoing treatment for mental illness."