Profiling Homicides Based on Impulsive or Proactive Natures in Male Schizophrenia Patients

Article Figures & Data

Table 1

Background Characteristics of the Study Sample

	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 = .035^{^a}
Unemployed/irregular work at the time of index offense	40 (85.1)	24 (88.9)	16 (80)	χ² = . 716; p = .438^{^a}
Poor social support at the time of index offense	8 (17)	7 (25.9)	1 (5)	χ² = 3.562; p = .114^{^a}
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 = .737^{^a}
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 = .220^{^a}
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 = .638^{^a}

↵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 = .251^{^a}
Multiple victims	5	10.6	3	11.1	2	10	χ² = . 015; p = 1.000^{^a}
Treatment nonadherence in the index homicide	42	89.4	24	88.9	18	90	χ² = . 015; p = 1.000^{^a}
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
Firearms^{^b}	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
Infidelity^{^b}	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

↵^aFisher’s exact test.
↵^bPost-hoc between-group proportions (impulsive vs. proactive) show significant differences.
p < .05 statistically significant (bold values).

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 Total^{^a}	78.59 ± 11.70	74.55 ± 11.89	1.163	.251
Attention^{^a}	19.96 ± 3.41	20.00 ± 4.60	−.032	.975
Motor^{^a}	25.67 ± 5.49	23.65 ± 4.23	1.367	.178
Nonplanning^{^a}	32.96 ± 4.75	30.90 ± 5.02	1.438	.157
PCL-R Total^{^a}	17.37 ± 6.90	17.80 ± 5.02	−.236	.815
PCL-R Factor 1^{^b}	8.30 ± 3.48	9.35 ± 2.18	−1.140	.254
Facet 1^{^b}	2.30 ± 2.25	2.15 ± 1.56	−.110	.913
Facet 2^{^b}	5.96 ± 1.91	7.20 ± 1.28	−2.760	.006
PCL-R Factor 2^{^a}	9.04 ± 3.51	8.45 ± 3.25	.584	.562
Facet 3^{^b}	6.52 ± 2.41	5.80 ± 2.28	−1.142	.254
Facet 4^{^b}	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

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).