Sussex Police neglected to document over 20,000 crimes within a year, and investigations were not consistently comprehensive, according to a watchdog report.
Inspectors indicated that the police department must enhance its documentation of serious crimes, including rape and domestic violence.
Nevertheless, HM Inspectorate of Constabulary (HMIC) commended the police for its community engagement.
Chief Constable Jo Shiner stated that the constabulary recognised the necessity to enhance “response and investigations”.
The assessment deemed the police “inadequate” in two domains: crime documentation and public response.
It estimated that 85.6% of all crime was being recorded, excluding fraud. A total of 20,200 crimes were not recorded over a 12-month period from 2021-22.
The force also “requires improvement” at investigating crime, the report said. Investigations “aren’t always thorough”, due to staff having high case-loads.
Roy Wilsher, HM Inspector of Constabulary, said: “I have concerns about how the force is responding to the public and about its crime recording standards.
“In view of these findings, I have been in contact with the chief constable and the police and crime commissioner, as I do not underestimate how much improvement is needed.”
Mr Wilsher highlighted “behavioural crimes” as being particularly bad at being recorded, such as harassment, including stalking, and controlling and coercive behaviour.
He also pointed to unrecorded rape crimes, domestic abuse and antisocial behaviour.
Ms Shiner said: “We acknowledge the recommendations made in the report and take these very seriously.
“We have worked closely with the inspectorate over the past nine months to accelerate action plans against these, having identified response and investigations as areas requiring intense focus through our own internal review process.”
The report estimated 79.4% of violent offences were recorded – leaving just over 20% unrecorded.
Of the 47 unrecorded violent crimes that were found, 19 were domestic abuse-related.
The report also estimated that the force failed to record almost 10% of sexual offences.
However, the force had demonstrated success at preventing crime and antisocial behaviour, inspectors said.
It was also praised for engaging with communities, including some which are “hard-to-reach”.
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