The Independent Office for Police Conduct (IOPC) invoked its rarely-used "power of initiative" after the force did not identify any conduct matters following a review into any reports which could have led to action being taken against the PC sooner.

Carrick, 48, was jailed for at least 30 years in February after he was unmasked as one of Britain's worst ever sex offenders.

The Met was forced to apologise and admit Carrick should have been rooted out earlier after it emerged he came to police attention over nine incidents before he was prosecuted, including allegations of rape, domestic violence and harassment between 2000 and 2021.

Four investigations have now been launched into the conduct of eight Met officers and one staff member by the IOPC in what the watchdog described as an "unusual step".

They centre on apparent failures to progress misconduct investigations against Carrick after criminal probes into his behaviour were dropped, allowing him to remain a police officer until his arrest in October 2021.

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IOPC regional director Mel Palmer said: "Our review has identified repeated failures to progress conduct investigations when the Met's DPS (department of professional standards) officers were advised that no further action was being taken by the forces carrying out the criminal investigations into Carrick.

"We were also deeply concerned to find that in respect of two of the cases, David Carrick's name was removed from the MPS's system records after the criminal investigations were dropped.

"This meant that some prior allegations made against Carrick did not show up in the system when further allegations were later made, leading to MPS officers being unable to build a complete picture of his pattern of offending.

"These were potentially missed opportunities to pursue gross misconduct investigations against Carrick, which may have led to his dismissal years before he was eventually arrested."

Six of those being investigated were in the Met's DPS at the time. Some of the officers - with ranks between constable and chief inspector, have now retired and one works for another force.