Detectives investigating the murder of special constable Nisha Patel-Nasri in north London say they have received "significant information".
Mrs Patel-Nasri was stabbed outside her home
Officers distributed posters and renewed house-to-house inquiries in Wembley, a week after the 29-year-old was stabbed outside her home.
A Scotland Yard spokesman said several calls contained significant information and had been acted on immediately.
Police are trying to trace a black hooded man seen running from the scene.
Police also want to trace another man seen walking away who did not look round as Mrs Patel-Nasri screamed.
Mrs Patel-Nasri is thought to have gone outside in her nightclothes to investigate suspicious noises.
Police believe her attacker may have used her own 13-inch kitchen knife to stab her just before midnight on 11 May.
Earlier that night, Mrs Patel-Nasri and her husband had dinner together to celebrate their third wedding anniversary, before she told him to go out to play snooker.
Her husband and brother both made heartfelt pleas earlier in the week for the public to help catch her killer.
Scotland Yard said they are aware of threats made towards Mr Nasri earlier in the year in connection with his limousine business.
High value cars were often parked outside their home and there has been speculation that these may have attracted thieves.
Possible links with an attempted burglary at the house on 6 May are also being looked into.