DCI Andy Partridge from the Met's Homicide and Serious Crime command tells ITV London they are still looking for witnesses to come forward to help solve the murder of Sabrina Moss.
Sabrina was shot on Kilburn High Street last Saturday while out celebrating her 24th birthday.
DCI Partridge said the Met want anyone who was in the area at the time to come forward, even if they think they only have a small amount of information - saying people "may not realise the significance of what they have seen".
Anyone with any information can call police on 101 or Crimestoppers anonymously on 0800 555 111.
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A 24-year-old man has been arrested on suspicion of murder after the body washed up on the Thames shoreline.
Seven people have now been arrested after a man died from serious head injuries
The 38-year-old officer was on his way home from a night shift when he collapsed. His death is not being treated as suspicious.