The London police service is being sued over failures which led to the fatal shooting of a New Zealand-born sergeant.
According to British media, Matt Ratana was shot by a handcuffed suspect in custody in September 2020. The BBC reported a coroner's inquest last year returned a verdict of unlawful killing.
Ratana, 54, who had served in the Met Police for almost 30 years and was three months from retirement, was hit in the chest by the first of three shots discharged in three seconds by Louis De Zoysa.
He had been arrested and searched but managed to hide an antique revolver in an underarm holster.
During the inquest, officer Rich Davey admitted he did not follow policy when he searched the suspect in south London before bringing him into custody - the inquest found police failures led to the shooting.
A Met Police spokesperson said it had received a civil claim in relation to the murder of Ratana and remained in dialogue with the claimant's legal representative.
They would not be commenting further while the claim remained ongoing.
