Seriousness of crime increases with offender's age - study

File photo / Rotorua Daily Post

Sixty-year-olds commit the most serious crimes on average, according to a new Statistics New Zealand study based on Ministry of Justice guidelines.

They rarely commit a crime, and in most categories - such as violent crimes - their offending is relatively harmless.

But when 60-year-olds are apprehended by police, it is likely to be for some of the worst drug offending, making their average crime the most serious of any age group.

Statistics New Zealand released the report today showing patterns in police apprehensions by demographic.

Police apprehended more 17-year-olds - at more than one apprehension for every five - than any other age demographic, and men were apprehended five times as often as women, the report says.

However, Statistics New Zealand also calculated the average "seriousness" of the apprehensions based on Ministry of Justice guidelines taking into account the likelihood and length of imprisonment.

The average seriousness of crimes slightly increased by age of the person apprehended, with a spike at 60.

By crime category, the seriousness of sexual offending peaked at about age 30 and drug offences at just past 60.

Anti-social offences - primarily disorderly behaviour - peaked at about 40 years old.

In other categories - such as property damage, violence and dishonesty, which includes theft - young people were apprehended both most often and for the most serious crimes, on average.

"This report on police apprehensions in New Zealand will contribute to the ongoing debate on crime in New Zealand.

"It's innovative, using a 'seriousness scale', which assigns weights to different offence categories," said social conditions business unit manager Conal Smith.

The survey looked at apprehensions from 2005 to 2009.

The median age for all apprehensions was 22 years, ranging from 19 years for dishonesty offences, to 32 years for sexual offences.

The median age for sexual offence apprehensions was 33 years for men and 23 for women.

In most offence categories offending was shown to begin from around the age of 10 years, increasing rapidly to peak at around 17 years, and subsequently decreasing with advancing age.

Male arrests were generally for more serious offences than female apprehensions, particularly in the violence and dishonesty offence categories.

Males were also far more likely to be apprehended for offences than females, with a range from 98 per cent of apprehensions for sexual offences being males, to 74 per cent of arrests for dishonesty offences being males.

The report also looked at how different offences were dealt with: warnings or cautions were issued in 13 per cent of all apprehensions (for those 17 years of age and older) over the four years of the report.

Generally, police were more likely to deal with less serious offences by using a warning or caution. For example, the warning/caution rate was 32 per cent for minor assaults, compared with only 2 per cent for grievous assaults.