West Midlands Police will be put into special measures, inspectors have said, following a series of failings including poor investigations.
His Majesty’s Chief Inspector of Constabulary (HMIC) said the force has been moved into an enhanced level of monitoring.
The force is not carrying out investigations “which lead to satisfactory results for victims”, or effectively managing the risk posed to the public by registered sex offenders, the inspectorate said.
The chief constable of West Midlands Police said he “completely disagrees” with the decision.
The force said many of the issues raised by inspectors related to a previous operating model.
It said statistics were “largely drawn” from that before a new model was introduced in April this year, adding it was outperforming other forces in solving burglary, robbery and homicide cases.
HMIC said while it was assured the force is taking steps to address concerns, “significant and sustained improvements” were needed.
WMP Chief Constable Craig Guildford said: “Although I remain respectful of HMICFRS, I completely disagree with their decision-making to move West Midlands Police into Engage now despite providing them with recent evidence that should inform a much more comprehensive and fair assessment of the force.
“Our job now is to ensure the plans we have already implemented expeditiously address HMICFRS’ concerns.”
Constable Guildford also said it was “misleading” for the inspectorate to say victims were not safeguarded – and domestic abuse arrest rates have increased from 27% to 39%.
The force also answers 70,000 999 calls a month in an average of five seconds, with “significant reductions in crime”, the police chief said.
He acknowledged issues around the force’s management of sex and online child abuse offenders, but said these had been identified and were a “legacy” of the force’s previous operating model.
Constable Guildford also accepted “investigations need to improve further” but said the force had a “detailed plan” to achieve this.
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His Majesty’s inspector of constabulary, Wendy Williams, said: “West Midlands Police has been asked to urgently produce an improvement plan and will meet regularly with our inspectors.
“We will work closely with the force to monitor its progress against these important and necessary changes.”
The country’s second-largest force joins the biggest, the Metropolitan Police, in special measures along with Devon and Cornwall, Staffordshire, Wiltshire.