Non-sexual violence in Scotland: report

5 Perpetrators of violent crime 

5.1 What do we know about perpetrators of violent crime?

5.1.1 Trends in the ages of perpetrators of violent crime

 Key Findings:

There has been a fall in the percentage of SCJS violent incidents which involved perpetrators aged 16 to 24 from 46% in 2008-09 to 23% in 2017-18.  However, findings still suggest that perpetrators of violent crime tend to be from younger age groups (under 40).  

Police Recorded Crime data suggests the median age of perpetrators for several types of violence has increased since 2008-09, driven by a fall in those aged 16 to 24 years old. 

Criminal Proceedings data shows the reductions in convictions for non-sexual crimes of violence and Common assault over the past ten years have been driven by a fall in those aged under 30.

Scottish Crime and Justice Survey

The SCJS found that violent crimes in 2017-18 were perpetrated by individuals from a range of age groups (Figure 10). However, only around one in every four incidents (23%) involved a perpetrator over the age of 40, suggesting perpetrators tended to be from younger cohorts^[23].

Figure 10: Percentage of violent crime incidents involving offenders of each age group

Base: Violent crime incidents where respondent could say something about offender (120); Variable: QAGE
Source: Scottish Crime and Justice Survey, 2017-18

Police Recorded Crime

Most Police Recorded Crime statistics do not include information on perpetrator age – however some findings are available from additional studies of this data (based on a review of crime records) and other statistical sources, like the Homicide National Statistics.

The median age of a Homicide perpetrator over the three years ending 2017-18 was 31 years old, compared to 26 years old for the three years ending 2008-09 (Table 18). Between those two periods the number of Homicide perpetrators fell by 49%, from 450 during the three years ending 2008-09 to 228 during the three years ending 2017-18. Most of this reduction was due to falls in the number of 16 to 24 year old perpetrators (down from 188 to 61) and to a lesser extent those aged 25 to 39 years old (down from 157 to 102 perpetrators).

Perpetrators of Attempted murder & Serious assault were also older in 2017-18 than perpetrators in 2008-09 - with their median age increasing from 23 to 27 years old. The volume of these crimes fell by 35% between those years, driven by reductions in perpetrators aged 16 to 24 years old (Table 19). For example, the estimated number of crimes with at least one perpetrator aged 16 to 24 years old fell from 2,610 in 2008-09 to 1,250 by 2017-18 (or from 40% of all perpetrators to 30%).

Despite these reductions, those aged 16 to 24 were still the most likely to commit Attempted murder & Serious assault, with an estimated 26.9 perpetrators per 10,000 population (compared to 9.8 for all ages) (Figure 11). However this rate has more than halved since 2008-09 (when it was 62.1 perpetrators per 10,000 population), with much less change in rates for the other age groups.

Figure 11: Number of perpetrators of Attempted murder & Serious assault per 10,000 population according to age of perpetrator, 2008-09 and 2017-18.

Source: Analysis of Police Recorded Crime records, 2008-09 & 2017-18

Perpetrators of Robbery were older in 2017-18 than perpetrators in 2008-09 – with their median age increasing from 23 to 28 years old. The volume of these crimes fell by 47% between those years, driven by reductions in perpetrators aged 16 to 24, and to a lesser extent those aged 25 to 39 years old (Table 20). At an estimated 10.4 perpetrators per 10,000 population in 2017-18, those aged 16 to 24 years old still remain the most likely to commit a Robbery (compared to 4.6 for all ages). However their rate is now only slightly higher than those aged 25 to 39 years old, having fallen 63% from an estimated 28.2 perpetrators per 10,000 population in 2008-09 (Figure 12).

Figure 12: Number of perpetrators of Robbery per 10,000 population according to age of perpetrator, 2008-09 and 2017-18.

Source: Analysis of Police Recorded Crime records, 2008-09 & 2017-18

Criminal Proceedings^[24]

The reduction in convictions for non-sexual crimes of violence over the past ten years has been driven by a fall in convictions for those aged under 30, most notably those aged between 18 and 25 years old (Figure 13). The median age of males convicted for these crimes increased from 23 years in 2008-09 to 28 years in 2017-18. Over the same period, the median age for females convicted increased from 26 years to 32 years. 

In 2008-09, convictions of Common assault peaked at 18 years of age for males and 17 years of age for females (20.2 convictions per 1,000 population and 6 convictions per 1,000 respectively) and decreased gradually with increasing age. However, by 2017-18, both these peaks had fallen, to 7.6 convictions per 1,000 population for males, and 2 convictions per 1,000 population for females.

In 2017-18, although there was a slight variation in convictions in different year groups, the number of convictions per 1,000 population was the same for 18 year old men as it was for 30 year old men (7.6 per 1,000). For ages over 30, the conviction rate for males followed a very similar pattern to that seen in 2008-09. For females aged up to 30, there were fewer convictions per 1,000 population in 2017-18 than in 2008-09. However, for almost every age older than 30, there were slightly more convictions per 1,000 population in 2017-18 than there were in 2008-09.

Figure 13: Non-sexual crimes of violence - convictions per 1,000 population by year of age.

Source: Analysis of Criminal Proceedings Database, 2008-09 & 2017-18

Over the past ten years, the median age for males convicted of Common assault increased from 26 in 2008-09 to 30 in 2017-18. In 2017-18, the number of convictions for Common assault per 1,000 population was broadly the same for 18 year old males as it was for 30 year old males (7.6 per 1,000 population) (Figure 14). Thereafter, the conviction rate for males followed a very similar pattern to that seen in 2008-09. 

Similarly, the median age for females convicted for Common assault increased from 26 to 31 years old between 2008-09 and 2017-18. There has been a small change in the number of females convicted of Common assault over the past decade with 0.9 convictions per 1,000 population in 2008-09 and 0.8 convictions per 1,000 population in 2017-18.

Overall, there has been a very small decrease in female convictions for Common assault in the last decade. However, this overall small decrease comprises a larger decrease in convictions for those females aged under 30 (most notably for 17 year olds) balanced by a small increase in convictions for most years from age 30 (Figure 15). This has resulted in a much wider, more even spread of ages for females convicted of Common assault.

Figure 14: Common Assault - convictions per 1,000 population by year of age (male convictions).

Source: Analysis of Criminal Proceedings Database, 2008-09 & 2017-18

Figure 15: Common Assault - convictions per 1,000 population by year of age (female convictions).

Source: Analysis of Criminal Proceedings Database, 2008-09 & 2017-18

Note: The axis in Figure 15 matches that in Figure 14 to aid comparison of volumes.

Table 18: Homicide accused by age group, 2008-09 & 2017-18.

Age Group	3 years ending 2008-09		3 years ending 2017-18		2008-09 to 2017-18 change
	%	Total Volume	%	Total Volume	% Point Change	Total Volume Change
Under 16	2.7%	12	1.3%	3	⇓ by 1.4%	-9
16 to 24	41.8%	188	26.8%	61	⇓ by 15.0%	-127
25 to 39	34.9%	157	44.7%	102	⇑ by 9.8%	-55
40+	20.7%	93	27.2%	62	⇑ by 6.5%	-31
Median age of perpetrator1	26 years old		31 years old
All recorded Homicide2	100%	450	100%	228	n/a	-222

¹Three year moving average age; ²Numbers may not sum to 100% due to rounding. 

Source: Homicide National Statistics, 2017-18

Table 19: Attempted murder & Serious assault perpetrators by age group, 2008-09 & 2017-18.

Perpetrator’s Age Group	2008-09		2017-18		2008-09 to 2017-18 change
	%	Est. Volume	%	Est. Volume	% Point Change	Est. Volume Change
Under 16	5.1%	330	6.7%	280	No change	-50
16 to 24	40.4%	2,610	29.9%	1,250	⇓ by 10.5%	-1,360
25 to 39	31.3%	2,020	43.4%	1,820	⇑ by 12.1%	-200
40+	12.0%	780	16.5%	690	No change	-90
Unknown	18.4%	1,190	9.4%	610	⇓ by 9.0%	-580
Median age of perpetrator	23 years old		27 years old
Total Attempted murder & Serious assault1,2	100%	6,472	100%	4,189	n/a	-2,283

¹ Numbers may not sum to 100% due to rounding; ²Based on a sample of crime records (550 from 2008-09 and 551 from 2017-18)

Source: Analysis of Police Recorded Crime records, 2008-09 & 2017-18.

Table 20: Robbery perpetrators by age group, 2008-09 & 2017-18.

Perpetrator’s Age Group	2008-09		2017-18		2008-09 to 2017-18 change
	%	Est. Volume	%	Est. Volume	% Point Change	Est. Volume Change
Under 16	7.5%	220	5.4%	80	No change	-140
16 to 24	36.9%	1,090	22.0%	340	⇓ by 14.9%	-750
25 to 39	38.2%	1,130	41.7%	650	No change	-480
40+	6.5%	190	12.3%	190	by 5.8%	0
Unknown	14.8%	440	12.9%	200	No change	-240
Median age of perpetrator	23 years old		28 years old
Total Robbery1, 2	100%	2,963	100%	1,556	n/a	-1,407

¹ Numbers may not sum to 100% due to rounding; ²Based on a sample of crime records (501 from 2008-09 and 450 from 2017-18)

Source: Analysis of Police Recorded Crime records, 2008-09 & 2017-18

5.1.2 Gender of perpetrators of violent crime

 Key Findings:

Across all major data sources (SCJS, Police Recorded Crime and Criminal Proceedings), the clear majority of violent crimes in 2017-18 were carried out by a male perpetrator. 

The fall in levels of non-sexual violent crime since 2008-09 has been driven by fewer cases involving a male perpetrator.

Scottish Crime and Justice Survey

In 98% of violent incidents reported in the 2017-18 SCJS, respondents were able to provide some information about who committed the crime^[25]. All findings are proportions of cases where respondents were able to say something about the person or people who carried out the offence, unless otherwise stated. 

The SCJS results highlight that the clear majority of violent crimes in 2017-18 (78%) were carried out by male perpetrators only, which is consistent with previous years. Female perpetrators only were involved in 15% of incidents, whilst in 7% of cases both men and women were responsible. 

In the self-completion section of the survey, respondents are asked if they have experienced Partner abuse, and if so are also asked the gender of the perpetrator. In 2016-18^[26], of those who had experienced Partner abuse since the age of 16, 67% said the abuser was male, and 30% said the abuser was female. Less than 1% stated that both male and female partners had perpetuated abuse^[27]. Breaking this down by the gender of respondents, abusive partners were overwhelmingly of the opposite gender - 97% of female respondents were abused by a male partner, and 88% of male respondents were abused by a female partner. 

Police Recorded Crime

Most Police Recorded Crime statistics do not include information on perpetrator gender – however some findings are available from additional studies of this data (based on a review of crime records) and other statistical sources, like the Homicide National Statistics.

Most perpetrators of Homicide for the three years ending 2017-18 were male (89%). This has remained unchanged since the three years ending 2008-09 (Table 21). Looking at these trends over time for Homicide (Figure 16), there has been a noticeable decrease in the overall number of perpetrators, with most of this change accounted for by a fall in male perpetrators. 

Figure 16: Total number of Homicide perpetrators, and Homicide perpetrators by gender, Scotland, three years ending 1996-97 to three years ending 2017-18.

Source: Homicide National Statistics, 2017-18

The clear majority (84%) of Attempted murder & Serious assaults had a male or all male group of perpetrators in 2017-18 (Table 22). This is similar to the figure in 2008-09 (82%). In 2017-18, only 10% had a female or all female group of perpetrators, whilst the remaining 6% had a mixed gender group or a perpetrator of unknown gender. Attempted murder & Serious assault with a male or all male group of perpetrators is estimated to have fallen by 1,810 between 2008-09 and 2017-18, from 5,330 to 3,520. This fall accounts for the clear majority (around 80%) of the total reduction in these crimes since 2008-09.

Around five out of every six Robberies (82%) had a male or all male group of perpetrators in 2017-18 (Table 23). This has fallen from 88% in 2008-09. Only 6% of Robberies in 2017-18 had a female or all female group of perpetrators, whilst the remaining 12% had a mixed gender group or a perpetrator of unknown gender. Robbery with a male or all male group of perpetrators is estimated to have fallen by 1,340 between 2008-09 and 2017-18, from 2,610 to 1,270. This fall accounts for almost all of the total reduction in Police Recorded Robbery between those two years.

An earlier study into Common assault^[28] recorded by the police in 2014-15 found that around three quarters (74%) of perpetrators were male. Around a quarter (24%) of were female while the remaining 2% were mixed gender groups or unknown.

Criminal Proceedings

A separate analysis was conducted on the profile of people convicted of non-sexual crimes of violence and Common assault, based on data from the Criminal Proceedings database^[29]. This showed that the vast majority of these crimes were carried out by a male perpetrator. Between 2008-09 and 2017-18, males accounted for between 87% and 88% of all convicted.

Further to this, the number of Common Assault convictions per 1,000 population for men has fallen in the past decade, from 4.5 per 1,000 population in 2008-09 to 2.9 per 1,000 population in 2017-18. Over the same period, the number of female convictions for Common Assault remained relatively unchanged (dropping from 0.9 convictions per 1,000 population in 2008-09 to 0.8 in 2017-18). 

Table 21: All recorded Homicide perpetrators by gender, three years ending 2008-09 & 2017-18.

Perpetrator’s Gender	3 years ending 2008-09		3 years ending 2017-18		2008-09 to 2017-18 change
	%	Volume	%	Volume	% Point Change	Volume Change
Male	89%	401	89%	204	<1%	-197
Female	11%	49	11%	24	<1%	-25
All recorded Homicide where known1	100%	450	100%	228	n/a	-222

¹ Numbers may not sum to 100% due to rounding
Source: Homicide National Statistics, 2017-18

Table 22: Attempted murder & Serious assault perpetrators by gender, 2008-09 & 2017-18.

Perpetrator’s Gender	2008-09		2017-18		2008-09 to 2017-18 change
	%	Est. Volume	%	Est. Volume	% Point Change	Est. Volume Change
Male / All male	82%	5,330	84%	3,520	No Change	-1,810
Female / All female	8%	490	10%	410	No Change	-80
Mixed Group / Other / Unknown	10%	650	6%	260	No Change	-390
Total Attempted murder & Serious assault1,2	100%	6,472	100%	4,189	n/a	-2,283

¹ Numbers may not sum to 100% due to rounding; ²Based on a sample of crime records (550 from 2008-09 and 551 from 2017-18)

Source: Analysis of Police Recorded Crime records, 2008-09 & 2017-18.

Table 23: Robbery perpetrators by gender, 2008-09 & 2017-18.

Perpetrator’s Gender	2008-09		2017-18		2008-09 to 2017-18 change
	%	Est. Volume	%	Est. Volume	% Point Change	Est. Volume Change
Male / All male group	88%	2,610	82%	1,270	⇓ by 6%	-1,340
Female / All female group	4%	120	6%	100	No Change	-20
Mixed Group / Other / Unknown	8%	230	12%	180	No Change	-50
Total Robbery1,2	100%	2,963	100%	1,556	n/a	-1,407

¹ Numbers may not sum to 100% due to rounding; ²Based on a sample of crime records (501 from 2008-09 and 450 from 2017-18)

Source: Analysis of Police Recorded Crime records, 2008-09 & 2017-18

5.2 The relationship between victims and perpetrators of violent crime

 Key Findings:

Both the SCJS and Police Recorded Crime data suggest that, in general, perpetrators of violent crime are known to the victim. The exception to this is Robbery, most of which is committed by someone not known to the victim.

While the majority of Homicide victims are killed by someone known to them, males are more likely to be killed by an acquaintance whereas females are more likely to be killed by a partner or ex-partner.

Females are more likely to be the victim of Attempted murder & Serious assault, and Common assault committed by a partner or ex-partner.

Over the past ten years, almost all of the reduction in Robbery has been driven by fewer crimes committed by strangers.

Scottish Crime and Justice Survey

The SCJS found that in 2017-18, most violent incidents (74%) were committed by people who the victims knew or had seen before. Where perpetrators where known by the victim, more than two-thirds of incidents (68%) were said to have involved people ‘known well’.

Police Recorded Crime

Most Police Recorded Crime statistics do not include information on the relationship between the victim and perpetrator – however some findings are available from additional studies of this data (based on a review of crime records) and other statistical sources, like the Homicide National Statistics.

Where a violent crime is recorded by the police, in general, the perpetrator was known to the victim. For example, in 2017-18, 68% of Homicide victims over the three years ending 2017-18 knew the perpetrator, as too did 66% of Attempted murder & Serious assault victims. An earlier 2014-15 study of Common Assault found that around three-fifths (61%) of cases involved a victim who knew the perpetrator. One type of non-sexual violent crime with a different pattern is Robbery, where the majority of cases in 2017-18 (63%) involved a perpetrator not known to the victim. 

Looking at Homicide over the longer term, again the majority of victims were killed by someone they knew (Table 24) including 76% of those killed between 2008-09 and 2017-18. Of all Homicide victims in the last ten years, half (51%) were killed by an acquaintance, 15% by a partner or ex-partner and around one in ten (11%) by a relative. Males were more likely to be killed by an acquaintance (59%) compared with females (27%), whereas females were more likely to be killed by a partner or ex-partner (43%) compared to males (5%).

Females are more likely to be the victim of Attempted murder & Serious assault by a partner or ex-partner than males. In 2017-18, 44% of Attempted murder & Serious assault with a female victim was committed by a partner or ex-partner, compared to 3% of Attempted murder & Serious assault with a male victim.

Similarly, females are more likely to be the victim of a Common assault committed by a partner or ex-partner than males. In 2014-15, 46% of Common assault with a female victim involved a partner or ex-partner as perpetrator, compared to 14% of Common assault with a male victim.

Over the past ten years the number of victims of Homicide fell by over two-fifths (46% or 150 victims) from 327 for the three years ending 2008-09 to 177 for the three years ending 2017-18. This reduction has been driven, in part, by Homicides where the victim knew the perpetrator.

Almost all of the reduction over the past ten years in Robbery has been driven by fewer crimes committed by strangers (Table 25). For example there were an estimated 2,240 Robberies where the victim did not know the perpetrator in 2008-09, falling by 1,250 crimes to 990 by 2017-18. At the same time there was no change between 2008-09 and 2017-18 in the estimated volume of Robberies where the victim knew the perpetrator. 

Changes in the relationship profile of victims / perpetrators for Attempted murder & Serious assault should be treated with more caution as the proportion of cases with an ‘unknown’ relationship fell from 21% in 2008-09 to 12% in 2017-18 (Table 26). Over the past ten years the number of crimes of Attempted murder & Serious assault where the perpetrator was not known to the victim fell by an estimated 800 cases from 1,710 in 2008-09 to 910 in 2017-18. Whereas, crimes where the victim did know the perpetrator fell by an estimated 610 crimes from 3,380 in 2008-09 to 2,770 in 2017-18.

Table 24: Relationship of main Homicide perpetrator to victim for all victims between 2008-09 to 2017-18.

Relationship	Male victims		Female victims		All victims
	%	Volume	%	Volume	%	Volume
Known to	73%	398	86%	157	76%	555
Acquaintances	59%	321	27%	49	51%	370
Partner / ex-partner	5%	29	43%	78	15%	107
Relatives	9%	58	16%	30	11%	78
Strangers	21%	117	9%	17	18%	134
Unknown	6%	31	4%	8	5%	39
All recorded Homicide victims1,2	100%	546	100%	182	100%	728

¹ Numbers may not sum to 100% due to rounding; ² For all Homicides where a perpetrator has been identified.        

Source: Homicide National Statistics, 2017-18

 Table 25: Relationship between Robbery victims and perpetrators, 2008-09 & 2017-18. 

Relationship	2008-09		2017-18		2008-09 to 2017-18 change
	%	Est. Volume	%	Est. Volume	% Point Change	Est. Volume Change
Robbery
Known to victim	18%	530	34%	530	⇓ by 16%	No Change
Not known to victim	76%	2,240	63%	990	⇑ by 12%	-1,250
Unknown	7%	200	2%	40	No Change	-160
Total Robbery1,2	100%	2,963	100%	1,556	n/a	-1,407

¹ Numbers may not sum to 100% due to rounding; ² Based on a sample of crime records (501 from 2008-09 and 450 from 2017-18)

Source: Analysis of Police Recorded Crime records, 2008-09 & 2017-18.

 Table 26: Relationship between Attempted murder & Serious assault victims and perpetrators, 2008-09 & 2017-18.

Relationship	2008-09		2017-18		2008-09 to 2017-18 change
	%	Est. Volume	%	Est. Volume	% Point Change	Est. Volume Change
Attempted murder & Serious assault
Known to victim	52%	3,380	66%	2,770	⇓ by 14%	-610
Not known to victim	26%	1,710	22%	910	No Change	-800
Unknown	21%	1.390	12%	500	⇑ by 9%	-890
All recorded  Attempted murder & Serious assault1,2	100%	6,472	100%	4,189	n/a	-2,283

¹ Numbers may not sum to 100% due to rounding; from 2017-18) ; ² Based on a sample of crime records (550 from 2008-09 and 551 from 2017-18) 

Source: Analysis of Police Recorded Crime records, 2008-09 & 2017-18.