It has emerged the 24-year-old woman who was fatally shot in Kilburn on Saturday was a nursery teacher.
Sabrina Moss, who had a four-year-old son, was on a night out celebrating her birthday when she was killed.
Police have now arrested a second man in connection with her murder.
Another woman, who was also shot, is in a stable condition in hospital.
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The property developer painted the mews house in March last year after she was denied permission for a basement below the property.
Profits at the estate agent plummeted 42% in the first half of the year.
Ionut Gheorghe, 27, was detained in Los Molinos near Madrid on Friday by Spanish police under a European Arrest Warrant.