Article Figures & Data
Tables
All Subjects (N = 47) Predominantly Impulsive (n = 27) Predominantly Proactive (n = 20) Mean±SD / n (%) Mean±SD / n (%) Test Statistics, p Age 44.74 ± 10.89 42.07 ± 11.61 48.35 ± 8.89 t = −1.646; p = .107 Education (years) 7.98 ± 3.76 7.93 ± 3.35 8.05 ± 4.36 Z = −.362; p = .717 Unmarried at the time of index offense 36 (76.6) 24 (88.9) 12 (60) χ2 = 5.349; p = .035a Unemployed/irregular work at the time of index offense 40 (85.1) 24 (88.9) 16 (80) χ2 = . 716; p = .438a Poor social support at the time of index offense 8 (17) 7 (25.9) 1 (5) χ2 = 3.562; p = .114a Childhood adversity 25 (53.2) 14 (51.9) 11 (55) χ2 = . 046; p = .831 History of AUD 17 (36.2) 11 (40.7) 6 (30) χ2 = . 574; p = .449 History of SUD 11 (23.4) 7 (25.9) 4 (20) χ2 = . 225; p = .737a Criminal history in a next of kin 17 (36.2) 11 (40.7) 6 (30) χ2 = . 574; p = .449 Age at illness onset 26.78 ± 9.15 24 ± 7.95 30.55 ± 9.48 Z = −2.621; p = .009 Duration of illness (years) 18.02 ± 10.51 18.15 ± 10.66 17.85 ± 10.58 t = .095; p = .925 Any conviction prior to homicide 7 (15.9) 6 (22.2) 1 (5.9) χ2 = 2.082; p = .220a Age at first offense 32.36 ± 10.83 30 ± 10.53 35.55 ± 10.66 t = −1.777; p = .082 Age at the index homicide 33.42 ± 10.3 31.48 ± 9.81 36.05 ± 10.61 t = −1.524; p = .134 Reoffending 17 (36.2) 10 (37) 7 (35) χ2 = . 021; p = .886 Recidividated homicide 5 (10.6) 2 (7.4) 3 (15) χ2 = . 697; p = .638a ↵SD: Standard deviation; AUD: Alcohol use disorder; SUD: Substance use disorder.
aFisher’s exact test, p < .05 (Bold values).
- Table 2
Comparison of Characteristics Surrounding the Homicides Between Predominantly Impulsive and Proactive Groups
All Subjects (N = 47) Predominant Impulsive (n = 27) Predominant Proactive (n = 20) n % n % n % Test Statistics, p Psychotically motivated homicide 44 93.6 24 88.9 20 100 χ2 = 2.374; p = .251a Multiple victims 5 10.6 3 11.1 2 10 χ2 = . 015; p = 1.000a Treatment nonadherence in the index homicide 42 89.4 24 88.9 18 90 χ2 = . 015; p = 1.000a Victim-perpetrator relationship χ2 = 8.096; p = .424 Parents 14 29.8 8 29.6 6 30 Intimate partner 5 10.6 1 3.7 4 20 Children 1 2.1 0 0 1 5 Siblings 6 12.8 4 14.8 2 10 Nonfamily acquaintance 17 36.1 11 40.8 6 30 Stranger 4 8.5 3 11.1 1 5 Method/weapon χ2 = 8.646; p = .029 Sharp instrument 32 68.1 21 77.8 11 55 Firearmsb 7 14.9 1 3.7 6 30 Blunt 5 10.6 4 14.8 1 5.0 Strangulation 2 4.3 1 3.7 1 5 Pushing from a height 1 2.1 0 0 1 5 Place χ2 = 2.605; p = .107 Public place 18 38.3 13 48.1 5 25 Private property 29 61.7 14 51.9 15 75 Intoxicated offender χ2 = 1.897; p = .387 No 39 83 21 77.8 18 90 Alcohol 6 12.8 4 14.8 2 10 Drugs 2 4.3 2 7.4 0 0 Accompanying delusions χ2 = 13.653; p = .006 No 4 8.5 4 14.8 0 0 Persecutory/threat 15 31.9 11 40.7 4 20 Referential/Control-override 6 12.8 5 18.5 1 5 Infidelityb 8 17 2 7.4 6 30 More than one type 14 29.8 5 18.5 9 45 Accompanying hallucinations χ2 = 3.758; p = .289 No 34 72.3 18 66.7 16 80 Auditory-Command 10 21.3 7 25.9 3 15 Auditory-Elementary 2 4.3 2 7.4 0 0 Visual 1 2.1 0 0 1 5 - Table 3
Impulsiveness and Psychopathy Scores of the Subjects According to the Predominant Violent Subtype of the Index Homicide
Predominantly Impulsive (n = 27) (Mean±SD) Predominantly Proactive (n = 20) (Mean±SD) t/Z p BIS-11 Totala 78.59 ± 11.70 74.55 ± 11.89 1.163 .251 Attentiona 19.96 ± 3.41 20.00 ± 4.60 −.032 .975 Motora 25.67 ± 5.49 23.65 ± 4.23 1.367 .178 Nonplanninga 32.96 ± 4.75 30.90 ± 5.02 1.438 .157 PCL-R Totala 17.37 ± 6.90 17.80 ± 5.02 −.236 .815 PCL-R Factor 1b 8.30 ± 3.48 9.35 ± 2.18 −1.140 .254 Facet 1b 2.30 ± 2.25 2.15 ± 1.56 −.110 .913 Facet 2b 5.96 ± 1.91 7.20 ± 1.28 −2.760 .006 PCL-R Factor 2a 9.04 ± 3.51 8.45 ± 3.25 .584 .562 Facet 3b 6.52 ± 2.41 5.80 ± 2.28 −1.142 .254 Facet 4b 2.67 ± 1.49 2.65 ± 1.69 −.324 .746 ↵SD: Standard deviation; BIS-11: Barratt Impulsiveness Scale; PCL-R: Psychopathy Checklist-Revised.
aStudent’s t test.
bMann-Whitnet U test.
p < 0.05 statistically significant (bold values).
- Table 4
Univariate and Multivariate Regression Analyses for Prediction of Being in the Predominantly Proactive Homicide Group
Univariate Multivariatea β Sig. Exp (B) [%95 CI] β Sig. Exp (B) [%95 CI] Marital status (married) 1.67 .028 5.333 [1.194–23.829] 2.30 .130 10.016 [.508–197.599] Age at illness onset .09 .025 1.095 [1.012–1.186] .01 .879 1.011 [.877–1.166] Method (firearms) 2.41 .033 11.143 [1.217–102.029] 1.63 .203 5.100 [.416–62.516] Infidelity delusions 2.41 .033 11.143 [1.217–102.029] 3.72 .026 23.268 [1.549–309.495] PCL-R Affective (Facet 2) 1.73 .025 1.734 [1.071–2.808] 1.18 .021 3.194 [1.189–8.576] PCL-R: Psychopathy Checklist-Revised.
↵aResults from binomial logistic regression, Model summary; χ2(38.176) = 25.934, p < 0.001, Percent correct classification 81% with R2 of 0.57.
p < .05 statistically significant (bold values).