Police are continuing to question Special Constable Nisha Patel-Nasri's husband, who has been arrested over her murder.
Fadi Nasri, 33, was held on suspicion of murder at an address in north London on Tuesday morning.
Mr Nasri, who runs a limousine business, is at a west London police station. He was the fourth man to be arrested over his wife's murder.
Scotland Yard confirmed the man remains in custody and will be questioned again on Wednesday.
A spokesman said: "The 33-year-old man was arrested at an address in north London and is currently in custody at a west London police station."
Police can hold Nasri for an initial 24-hour period, before applying to a superintendent for a further 12-hour extension.
It is understood that he no longer lives at the home he and his wife shared in Sudbury Avenue. He was arrested at a different residential address in north London, although police have refused to say where.
Another man, who is 37 and was arrested last year, is also being interviewed again today in connection with the case.
Two men, Tony Emmanuel, 41, of Clements Road, East Ham, east London, and Jason Jones, 35, of Hathaway Crescent, east London, have already been charged with Mrs Patel-Nasri's murder. They are next due at the Old Bailey on March 16.
Mrs Patel-Nasri, 29, died after being stabbed in the leg by an attacker outside her home in Sudbury Avenue, Wembley, north west London, on May 11.
