The news comes on the same day human remains were found in Kent – although these have yet to been identified as being those of Sarah. A police statement said: “Following the arrest of a police officer, the Metropolitan Police Service (MPS) made two referrals, one mandatory and one voluntary, to the Independent Office for Police Conduct (IOPC).
“These were linked to the conduct of the officer arrested on suspicion of kidnap, murder and indecent exposure.
“The IOPC has determined both these matters should be locally investigated by the MPS.”
The statement added: “We also made a mandatory referral in relation to the actions of police after Sarah was reported missing. We await the IOPC’s assessment.
“A further voluntary referral was made for a conduct matter in relation to the police investigation into the separate allegations of indecent exposure. The IOPC have determined this will be subject to an independent IOPC investigation.
“We have made another mandatory referral to the IOPC after the man arrested was taken to a hospital for treatment to a head injury sustained while in custody in a cell alone. He was being monitored by CCTV and received immediate first aid. We await the IOPC’s assessment.
“We are offering every assistance to the IOPC.”