During the period 2001–2015, there were 63 homicide deaths among adults aged 65 years and older (Fig. 1). Of these, there were 59 unique older adult homicide incidents: with 59 primary deceased victims (36 male, 23 female, Table 2) and 57 primary offenders (41 male, 16 female, Table 3). Homicide victims were more frequently younger than 75 years (n=37, 63%; median=72, IQR=11), while offenders were predominantly aged between 25 and 55 years (n=36, 63%; median=41, IQR=22).

Fig. 1

Case identification. a Source: Victoria Police Crime Statistics

Table 2 Overview of homicides among older adults (deceased), Victoria 2001–2015Table 3 Older adult homicide offenders, Victoria, 2001–2015Individual-level factorsDeceased

Among the 59 primary deceased homicide victims, six (10%) were employed at the time of their death (Table 2). Over one-third (n=22, 37%) were born overseas, of which nine (41%) had their main language recorded as not English. Two-thirds (n=39, 66%) had at least one diagnosed physical illness, of which 36% (n=14) were currently receiving treatment.

Almost 14% of deceased had a diagnosed mental illness recorded (n=8), and in a further 15% (n=9) a mental illness was suspected. There was a recorded history of alcohol and/or other illicit substance use for 14% (n=8). Eleven (19%) had been receiving psychiatric care proximal (within 6 weeks prior) to the homicide. Around one-quarter had experienced historical exposure to violence (n=15, 25%).

Almost half of the deceased (n=29) had previously been in contact with government or non-government human services, for most of which that contact was proximal (within 6 weeks prior) to the homicide (n=21, 36%). This contact was mainly with a general practitioner (GP)/family physician (n=10, 17%), social security (n=6, 10%) or other non-government agency (n= 5, 9%).

Offenders

Among the 57 primary offenders of older adult homicide, 19 (33%) were employed at the time of the homicide (Table 3). Of the 25% (n=14) of offenders that were born overseas, 43% (n=6) had their main language recorded as not English. Only 21% (n=12) had at least one diagnosed physical illness, of which 58% (n=7) had been receiving treatment.

Eighty-one per cent (n=46) of older adult homicide offenders had mental illnesses recorded as diagnosed (n=24), suspected (n=10) or a combination of diagnosed and suspected (n=12). Of the 36 with diagnosed mental illness, singular and multiple diagnoses were recorded, including substance use disorder (19, 53%), mood (affective) disorders (including bipolar affective disorder and depression) (n=17, 47%), schizophrenia, schizotypal and delusional disorders (n=10, 28%) and neurotic, somatoform and stress-related disorders (for example anxiety, PTSD and acute crisis) (n=9, 25%).

The majority had received psychiatric treatment at some time (n=28, 78%), with most receiving care proximal to the incident (n=21, 58%), most commonly by way of voluntary community treatment (n=17, 47%). Over half had a history of substance use (n=36, 63%) or history of exposure to violence (n=35, 61%).

Most offenders had previously been in contact with services (n=43, 75%), though less than one-half (n=26, 46%) had been proximal to the incident. Proximal service contacts included social services (n=14, 25%), police (n= 9, 16%), and family physicians/GPs, the law courts and drug and alcohol services (all 5, 9%).

Though differences were not statistically significant, female offenders had a higher incidence than males of historical exposure to violence (females n=11, 69%; males n=24, 59%), suicide ideation (females n=6, 38%; males n=6, 15%), suicide attempt (females n=5, 31%; males n=6, 15%), mental illness diagnoses (females n=12, 75%; males n=24, 59%), and proximal psychiatric treatment (females n=10, 63%; males n=14, 34%).

Interpersonal-level factors

Homicide deceased were primarily more than 25 years older than their offender (n=37, 62%), with the difference ranging between 25 and 64 years (median=34, IQR=22) (Online Resource 2). The deceased-offender relationship was largely intimate or familial (n=37, 63%), followed by friends and acquaintances (n=11, 19%) and strangers (n=8, 14%). Argument motive accounted for 15 (25%) of older adult homicides (Table 2). Motive was described as mental impairments such as psychosis, delusional, and drug and alcohol intoxication occurring in 13 incidents (22%).

Age difference was common at the case by case level, and the more common interactions were a male deceased and a male offender (n=24, 41%) and a female deceased and a male offender (n=17, 29%) (Fig. 2). The comparison also highlights greater substance use history, prior offending, diagnosed mental illness, and historical exposure to violence for the offender and physical illness and proximal service contacts for the deceased (Fig. 2).

Fig. 2

Dyadic (interpersonal) comparison of primary deceased and offender. The top graph depicts the number of incidents by sex within the deceased-offender relationship; the middle graph depicts the age of the deceased and offender by individual incident; and the bottom two graphs depict the presence of selected variables in either the deceased, the offender or both the deceased and offender, specifically: substance use history, presence of alcohol and drugs, prior offending, historical exposure to violence, diagnosed mental illness, physical illness, and proximal and non-proximal service contacts.

Incident-level factors

The incident location was predominantly the deceased’s home (n=43, 73%). Primary injury mechanisms were sharp object (n=21, 36%), bodily force (n=18, 31%) and blunt object (n=12, 20%). There was a positive toxicology screen for 29 (49%) of the deceased and alcohol and/or illicit drugs were detected 24 (42%) of offenders at the time of the incident (Tables 2 and 3; Fig. 2). An offender was identified in almost all incidents (n=58, 98%), charged in 86% (n=49) and sentenced in 65% (n=37) of the homicides. In the 12 cases where the offender was not sentenced, the outcome was primarily not guilty by reason of mental impairment (n=9), followed by acquitted or not fit to stand trial (n<5).

Community-level factors

Deceased victims commonly resided in a major city or a major city-inner regional area (n=50, 85% and n=47, 83%; Tables 2 and 3). The majority of victims and offenders were from the higher-level deciles (6th to 10th) for IRSD, indicating that they resided in communities with lower levels of socioeconomic disadvantage (deceased n=36, 62%; offenders n=31, 60%).

Older adult homicides by deceased-offender relationshipHomicide among persons in intimate or familial relationships

Among the 37 homicides that occurred among intimate partners (n=10) or family members (n=27), 48% (n=13) involved both a male deceased and offender (Online Resource 2). The home location was more frequent (n=31/37) and significantly different from the acquaintance (n=7/11) and stranger (n≤5/8) perpetrated homicides (Yates Continuity Correction 6.118 (1), p=.013, Phi .361). Compared with other relationship types, intimate or familial homicides involved a higher frequency of argument motive, and blunt object or bodily force mechanisms. A history of family violence was recorded for 15 (41%) incidents; eight deceased (22%) had been victims and seven (19%) were perpetrators of family violence.

Fourteen (38%) of the 37 intimate or familial homicides comprised a deceased parent killed by their adult child. The deceased were equally male or female (n=7), more offenders were male (n=10) and bodily force was the most common mechanism of injury (n=6). Within the parent-child relationship, 57% (n=8) of deceased had either perpetrated (n≤5) or been victims (n≤5) of violence.

Ten (27%) of the intimate or familial homicides occurred between intimate partners. More of the deceased were male (n=8), while offenders were equally divided between male and female (n=5). All incidents occurred at the deceased’s home or a residence shared with the offender. The most common mechanism of injury was a sharp object (n=5, 50%).

Homicides among other family members (n=13, 35%) included grandparents, aunts and uncles, in-laws and cousins, and more of the deceased were female (n=7, 54%). Eight (61%) were multiple fatality events (Online Resource 2).

Homicide among friends and acquaintances

Eleven (19%) of the 59 deceased were killed by friends and acquaintances. Over 80% of deceased were male (n=9, 82%), aged between 65 and 74 years (n=8, 73%), and were killed by other males (n=10, 91%). Over one-half of the deceased had been in contact with services at some time not proximal to the fatal incident (n=6, 55%) (Online Resource 2). These differed to intimate or familial and stranger relationship types in that the homicide occurred at the deceased’s home less often (n=7, 64%), was more often a single-fatality incident (n=10, 91%), involving a sharp object (n=6, 55%) and with offenders with an historical exposure to violence (n=9, 82%) and prior offending (n=7, 64%).

Homicide perpetrated by strangers

Eight (14%) of the 59 deceased were killed by strangers. The deceased were typically male (n=5, 63%) and aged between 65 and 74 years (n=5, 63%) (Online Resource 2). All stranger offenders had a substance use history, which was a significant difference to other relationship types (n=8, 100%; Yates Continuity Correction 3.743 (1), p=.021, Phi .309), and the incident location was significantly less frequently at home (Yates continuity correction 3.397(1), p=.037, Phi −.295). Offenders had more history of offending (n=6, 75%), diagnosed mental illness (n=7, 88%) and psychiatric treatment history (n=7, 88%) than for the other relationship types (Online Resource 2).