Table 2.
Incident characteristics* by homicide type, National Violent Death Reporting System, 2003–2017**
| Incidents | ||||
|---|---|---|---|---|
| Mass homicide n(%) |
Multiple homicide n(%) |
Single homicide n(%) |
Chi-square p-value | |
| Total | 141 | 3,439 | 74,623 | |
| Location of Incident | ||||
| Private home/apartment | 95 (67.4) b | 2,019 (58.7) c | 35,113 (47.1) | < 0.001 |
| Public location | 29 (20.6) a,b | 1,033 (30.0) c | 35,171 (47.1) | < 0.001 |
| More than one location | 16 (11.4) b | 328 (9.5) c | < 0.001 | |
| Unknown | 1 (0.7) b | 59 (1.7) c | 4,339 (5.8) | < 0.001 |
| Primary weapon used to inflict fatal injuries | ||||
| Firearm | 104 (74.3) a | 2,810 (82.3) c | 49,509 (69.2) | < 0.001 |
| Other | 36 (25.7) a | 604 (17.7) c | 22,062 (30.8) | < 0.001 |
| Number of weapons used to inflict fatal injuries | ||||
| 1 | 120 (85.7) a,b | 3,208 (93.5) c | 72,460 (99.6) | < 0.001 |
| 2 | 17 (12.1) a,b | 210 (6 1) c | 313 (0.4) | < 0.001 |
| 3+ | 3 (2.1) b | 14 (0.4) c | 0 (0) | < 0.001 |
| One or more nonfatally shot | 30 (21.3) b | 561 (16.3) c | 6,008 (8.1) | < 0.001 |
| Number nonfatally shot | ||||
| 0 | 107 (75.9) b | 2,774 (80.7) c | 62,525 (83.8) | < 0.001 |
| 1 | 14 (9.9) | 398 (11.6) c | 4,695 (6.3) | < 0.001 |
| 2 | 5 (3.6) | 95 (2.8) c | 920 (1.2) | < 0.001 |
| 3+ | 11 (7. 8) a,b | 68 (2.0) c | 393 (0.5) | < 0.001 |
| Unknown | 4 (2. 8) | 104 (3.0) c | 6,090 (8.2) | < 0.001 |
| Perpetrated by more than one suspect*** | 23 (18.3) | 563 (20.0) c | 9,106 (16.4) | < 0.001 |
| Circumstances d | ||||
| Interpersonal violence/life stressor | ||||
| Intimate partner violence-related | 41 (34.5) a,b | 622 (21.9) c | 9,637 (17.4) | < 0.001 |
| Family relationship problem e | 18 (28.1) a,b | 184 (12.0) c | 1,480 (5.2) | < 0.001 |
| Crisis during previous or upcoming 2 weeks f | 24 (27.3) a,b | 354 (16.7) c | 3,760 (9.4) | < 0.001 |
| Argument or conflict | 31 (26.1) b | 947 (33.3) c | 22,757 (41.1) | < 0.001 |
| Perpetrator of interpersonal violence in past month f | 13 (14.8) b | 202 (9.5) c | 1,697 (4.2) | < 0.001 |
| Other relationship problem (non-intimate or family) e | 4 (6.3) | 90 (5.9) | 1,473 (5.2) | 0.46 |
| Victim of interpersonal violence in past month f | 3 (3.4) | 54 (2.6) | 996 (2.5) | 0.84 |
| Jealousy (lovers’ triangle) | 3 (2.5) | 159 (5.6) c | 2,001 (3.6) | < 0.001 |
| Physical fight (2 people, not a brawl) e | 1 (1.6) b | 90 (5.9) c | 4,006 (14.0) | < 0.001 |
| Brawl | 1 (0 8) | 56 (2.0) | 1,223 (2.2) | 0.42 |
| Crime-related | ||||
| Drug involvement | 15 (12.6) | 513 (18.0) c | 7,175 (13.0) | < 0.001 |
| Gang-related | 7 (5.9) | 235 (8.3) c | 3,790 (6.8) | 0.01 |
| Drive-by shooting | 3 (2.5) | 151 (5.3) | 2,883 (5.2) | 0.41 |
| Hate crime | 2 (1.7) b | 10 (0.4) c | 73 (0.13) | < 0.001 |
| Terrorist attack | 2 (1.7) b | 4 (0.1) c | 6 (0.01) | < 0.001 |
| Walk by assault e | 0 (0) | 64 (4.2) c | 1,632 (5.7) | 0.01 |
| Other | ||||
| Victim(s) killed at work | 12 (10.1) a,b | 120 (4.2) c | 1,580 (2.9) | < 0.001 |
| Random violence f, **** | 7 (8.0) b | 77 (3.6) c | 861 (2.1) | < 0.001 |
| Victim used a weapon | 6 (5.0) | 257 (9.0) c | 3,209 (5.8) | < 0.001 |
| Victim was a bystander | 6 (5.0) b | 171 (6.0) c | 973 (1.8) | < 0.001 |
| Justifiable self defense | 5 (4.2) | 87 (3.1) | 1,584 (2.9) | 0.56 |
* To consolidate information about incidents with > 1 homicide, the authors developed an incident-level dataset with one record per incident (1 or more homicide victims) to describe all victims and suspects in the incident. This avoids overrepresenting data such as incident circumstances and suspect demographics associated with multi-victim homicides by counting these characteristics once per incident instead of once per victim
**All 50 U.S. states, the District of Columbia and Puerto Rico are currently funded to participate in NVDRS, but at the time of this study several of the newer states/jurisdictions had not yet completed a data collection cycle and therefore are not included. States and jurisdictions were first funded to participate in NVDRS in different years. Data for this study comes from the following 37 states/jurisdictions: Maryland, Massachusetts, New Jersey, Oregon, South Carolina, and Virginia (2003–2017); Alaska, Colorado, Georgia, North Carolina, Oklahoma, Rhode Island, and Wisconsin (2004–2017); Kentucky, New Mexico, and Utah (2005–2017); Ohio (2010–2017); Michigan (2014–2017); Arizona, Connecticut, Illinois, Indiana, Iowa, Kansas, Maine, Minnesota, New Hampshire, New York, Pennsylvania, Vermont, and Washington (2015–2017); Hawaii (2015–2016); California, Delaware, West Virginia, the District of Columbia, and Puerto Rico (2017). Illinois, Pennsylvania, and Washington collected data on ≥80% of violent deaths in their state, in accordance with requirements under which these states were funded. Data for California are for violent deaths that occurred in four counties (Los Angeles, Sacramento, Shasta, and Siskiyou)
*** Percentages are based on the number of incidents with known suspect information: mass (126), multiple (2,826), single (55,468). The sum of percentages in columns may exceed 100% because more than one circumstance could have been present per incident
****Random violence is defined as an act in which the suspect is not concerned with who is being harmed, just that someone is being harmed. An example of random violence is an incident in which a person who shoots randomly at passing cars from a highway bridge or opens fire in a crowded shopping mall
aStatistically significant difference (p < .05) of the prevalence between mass versus multiple homicide
bStatistically significant difference (p < .05) of the prevalence between mass versus single-victim homicide
cStatistically significant difference (p < .05) of the prevalence between multiple versus single-victim homicide
dUnless otherwise specified, percentages are based on incidents with known circumstances: Mass = 119; Multiple = 2,843; Single = 55,416
eCircumstances introduced in 2013; denominator adjusted to include only years 2013–2017
fCircumstances introduced in 2009; denominator adjusted to include only years 2009–2017