The Dublin Rape Crisis Centre has described the fact that up to 80% of sexual offences remain unsolved as demoralising and dispiriting for victims.
The CSO published new figures today showing that only a fifth of sex offences reported to the gardaí lead to a prosecution.
Garda headquarters said today it will publish data next year showing why cases have not been solved.
The CSO crime detection figures also show that while four out of five homicides are solved, just 8% of fraud and sexual offences are detected.
An Garda Síochána's ability to solve crime and gather sufficient evidence to bring offenders before the courts is fundamental to public confidence in the police service and justice system.
The figures show that a large volume of sex crimes and other offences which have been reported to gardaí have not been solved and the detection rate has fallen.
A total of 8% of sex offences were detected last year, compared to 9% in 2022.
The CSO also said that around one fifth of reported crime involving sexual offences lead to a charge or summons.
In total, 8% of fraud offences were detected, a figure that has remained static.
Less than one quarter of burglary (22%) and robbery (23%) offences were solved last year, while less that one third of thefts (31%) were detected.
The figures look better for violent, serious and organised crime with more than four in five homicides detected (82% up from 74%).
Almost four fifths of all drugs crime and three quarters of all weapons and explosives offences were also solved.
However, 28% of cases of assault, harassment and attempted murder were solved last year, a drop of three percentage points in the detection rate.
Overall, the figures show that detection rates in eight serious crime categories for 2023 was equal to or just below the rate for the previous year, and while the crime rates were found to be highest in Dublin, the detection rates in the capital were lowest.
Males were also nominated for over 90% of weapons, explosives, homicide and related offences, however females were suspected of carrying out more than one third (35%) of theft offences.
Men were identified as the suspected offender for most detected crimes, particularly for sexual offences where 92% of the offenders were male.
Males were also nominated for over 90% of weapons, explosives, homicide and related offences, however females were suspected of carrying out more than one third (35%) of theft offences.
Most offenders were aged between 18 and 24 when they committed the offences.
Gardaí said that the detection rate for crimes change over time as investigations are completed.
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A garda statement added that a crime can only be marked as detected when there has been a charge or other proceeding recorded.
"Incidents, such as sexual offences, can involve very complex and lengthy investigations, this means it can take many months from the time an incident is first reported for the crime to be fully investigated and for a charge to be directed.
"In recent years, An Garda Síochána has significantly developed our investigative capacity specifically in relation to sexual offences.
"Divisional Protective Service Units (DPSU), have been established in every Garda Division, under the direct supervision of a dedicated DPSU Inspector. These units, with the support of the Garda National Protective Service Unit, investigate sexual offences."
However, the Dublin Rape Crisis Centre said it expects around one-fifth of crimes linked to sexual offences lead to a charge or summons.
"This means that somewhere between 70-80% of sexual offences reported to gardaí remain undetected and while there are many reasons behind this figure, you can understand that from a victim's perspective it can be very dispiriting and demoralising when this happens.
"The CSO found that fewer than 4% of the women and men who have experienced sexual violence as an adult will report to gardaí and so the vast majority of people affected by sexual violence do not go this route."
