The Independent Office for Police Conduct (IOPC) said its independent probe follows a “conduct referral” from the force in relation to two officers, which was received on Wednesday night.
This is linked to four other referrals, and all are connected to the arrest of the serving Metropolitan Police officer currently being held on suspicion of kidnapping and murdering 33-year-old Ms Everard and for a separate allegation of indecent exposure, the IOPC said.
The IOPC said in a statement on Thursday night that its investigation will look at the actions of the Met after police received a report on February 28 that “a man had exposed himself at a fast food restaurant in South London”.
It added: “Yesterday we determined that two conduct referrals relating to kidnap/murder and indecent exposure allegations against the arrested officer should remain under local investigation by the force.
“We are still assessing a mandatory referral in relation to the actions of police after they received a report that Sarah Everard was missing.”
The IOPC said a fifth mandatory referral was received from the Met on Thursday “in relation to police contact with the arrested officer who was treated in hospital after sustaining a head injury while in custody yesterday afternoon”.
“That referral is also being assessed to determine what further action may be required from us,” the watchdog added.
The Metropolitan Police confirmed that, after the arrest of the officer, it made one “mandatory” and one “voluntary” referral to the IOPC – both linked to the suspect’s conduct – which the watchdog had determined should be locally investigated by the force.
It said in a statement: “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.”
The Met said it awaited the IOPC’s assessment of two other mandatory referrals in relation to police actions after Ms Everard was reported missing and 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,” the force said, adding: “We are offering every assistance to the IOPC.”