Only 9% of crimes end with suspects being charged or summonsed in England and Wales, Home Office figures suggest.
In the 12 months to March, 443,000 crimes resulted in a charge or summons out of 4.6 million offences - the lowest detection rate since 2015.
In sexual offence cases,
only 5% resulted in someone being charged or summonsed
Data also shows police closed nearly half (
48%) of all cases because no suspect could be identified.
It comes as new figures show the number of homicides has increased for the fourth year running.
The changing picture of how successfully police are catching criminals comes against a backdrop of rising crime.
Overall, crimes recorded by police went
up 11% in the year to March, figures published by the Office for National Statistics suggested.
The Home Office said that along with a growing caseload, there was evidence to suggest that more recorded crimes were in the most challenging offence types to investigate.
It gives the example of sexual offences -
up 24% on last year - giving officers a bigger workload and becoming more complex.
Rape cases take an average of 129 days to solve compared with, for example, two days for theft or criminal damage.