Although police officials have long recognized the need for two officers to respond on any kind of call with a potential for danger, a new study found that 34 percent of officers killed while responding to calls over a recent five-year period did not have backup when they were slain. In many of the cases, they were dispatched alone, and sometimes they simply did not wait for a second officer to arrive. The study also found that domestic disputes resulted in the highest portion of officer killings, 22 percent, followed by “disturbance” calls at 18 percent.

The new study, released Friday by the Justice Department’s Office of Community Oriented Policing Services, comes as the nation is reeling from the slaying of five officers in Dallas and three officers in Baton Rouge earlier this month, and then the killing of a gang-suppression officer in San Diego on Thursday night. So far this year, 34 police officers have been shot to death, compared with 19 during the same time last year, a 79 percent increase, according to the National Law Enforcement Officers Memorial Fund.

The NLEOMF provided the authors, Nick Breul and Mike Keith, and the data for the new analysis of 684 line-of-duty deaths in law enforcement from 2010 to 2014, to include not only police and sheriff’s departments but also corrections, federal and regulatory agencies across the country. The NLEOMF is widely recognized as the definitive source on tracking law enforcement fatalities.

Of the 684 law enforcement deaths in that five-year period, 272 were traffic related, most of which were not related to responding to a call, the study found. One hundred thirty-four other officers were shot while not responding to a call, often in ambushes in unprovoked attacks. And 146 officers died either from job-related illnesses or other accidents.

The purpose of the study was to focus on how to improve officer safety in either dispatched calls for service or self-initiated officer stops, which led study authors Breul and Keith to focus on the 132 remaining cases. Of those 132 deaths, 129 were by firearm, 92 of those by handgun. In the three non-gun-related deaths, one officer was pushed and fell to his death, one was stabbed, and one was struck by a vehicle.

Of the 91 dispatched calls resulting in death, 20 of them were domestic disputes, the largest category. In seven of those 20 cases, or 35 percent, only one officer was on the scene at the time of the shooting; in four cases, the officer was the only one dispatched, and in the other three, the officer did not wait for backup, Breul and Keith found.

Breul and Keith wrote that they “clearly understand the necessity in some circumstances for officers to act independently in order to immediately address a threat or to aid a person in imminent danger.” However, none of the cases they studied had those circumstances, and “subsequent review revealed that backup or swift mutual aid was available.”

Further, in eight of the domestic cases where two officers or more responded, they had been given information from a dispatcher or complainant that the suspect was armed or had a history of violence. “The need and use of coordinated information before handling a domestic-related call is critical,” Breul and Keith wrote. “The importance of call history, accurate information, and suspect descriptions cannot be overstated.”

Calls for disturbances, such as disorderly persons or noise complaints, were the next largest category of dispatched calls where officers were killed, with 16 of the 91 cases. Only one officer was present in nine of those 16 cases, Breul and Keith found. Even though they may sound like nuisance calls, “officers must avoid being lulled into a false sense of security by a call classification,” the authors wrote. “Officers must act together and not assume that it is a routine matter.”

Gary Cordner, an emeritus professor of criminal justice at Kutztown University of Pennsylvania, said he thought the recommendations in the report “were all pretty useful.” But he said that placing domestic calls as the most dangerous category was a function of separating out “crimes in progress.” And of the 91 dispatched line-of-duty deaths, 9 percent occurred during robberies, 9 percent during burglaries, 8 percent with shots fired and 3 percent were for theft, for a total of 29 percent of all such cases.

“If you put all those in one category,” Cordner said, “it would be the biggest category by a decent margin.” Overall, the 132 slayings is a minuscule percentage of the tens of millions of contacts that officers have with the public over five years, and Cordner said that makes it harder for every officer to be vigilant on every call, no matter how minor it seems.

Of the 91 dispatched cases studied, 31 of the officers, or 34 percent, were alone when they were killed. Of those 31 officers, 12 had been dispatched alone. In 41 of the 91 cases, or 45 percent, the officers had been advised that the suspect might be armed or threatening. In 18 of the cases, or 20 percent, the suspects were classified as having mental illness, the study found.

The study also looked at 41 cases where officers initiated the activity and died. Of those, 63 percent were traffic stops, and 17 percent were “suspicious person” and 12 percent were “suspicious vehicle” stops.

In the 26 fatal traffic stops, 11 were killed while speaking to the occupants, and half of the 26 cases involved only one occupant in the vehicle. Overall, the shooter was a passenger 54 percent of the time, and the driver 46 percent of the time. Breul and Keith noted that officers making traffic stops are at risk and should run the vehicle’s license plate before making contact and that “dispatchers must continually check on the welfare of officers who have marked out on a traffic stop.” They recommended that officers wear radio earpieces so wanted suspects cannot hear information about their status and to approach from the right side to protect against “struck-by crashes” as well as gain some distance and protection from an armed driver.

The study found that 81 percent of the officers killed in the 132 cases studied were wearing body armor, 14 percent were not and 5 percent were unknown. Most police body armor does not protect against the largest and most high-velocity rounds, nor does it protect every part of the body. The study found that 21 percent of the slain officers were killed by high-powered rifles.

Although most police departments long ago moved from two-officer to one-officer patrol cars, the debate over that switch never ended. Many departments recently moved temporarily to two-officer cars in the wake of the Dallas and Baton Rouge ambushes. Breul and Keith wrote that they “are not emphasizing two-man patrols but believe there is inherent safety of having multiple officers on the scene of those calls for service that are potentially dangerous and violent.”

The full study is here.

From The Washington Post