A £30,000 reward is being offered to help track down the killer of a special constable who was stabbed to death on her own doorstep.
Mrs Patel-Nasri was stabbed outside her home
Nisha Patel-Nasri was apparently investigating noises outside her home in Sudbury Avenue, Wembley, north-west London when she was attacked on 11 May.
Crimestoppers has put up the reward for information leading to the conviction of those responsible.
The Sun newspaper has also put up a £10,000 reward.
Mrs Patel-Nasri, 29, and her husband Fadi had been out celebrating their third wedding anniversary that night, but she was alone in the house at the time of the attack.
She was in her nightclothes when she was stabbed in the leg - it is thought she may have been attacked with her own knife - a John Lewis Evolution knife, which is missing from her kitchen.
A black, hooded, man was seen running towards nearby Sylvester Road and a man was also spotted walking in the opposite direction, apparently oblivious to her screams.
Police are also trying to trace four house keys that went missing three weeks before Mrs Patel-Nasri's murder and two cars spotted close to the scene.
One, an R-reg Rover, was seen in Charterhouse Avenue, 25 minutes after the stabbing and was later spotted parked in nearby Rugby Avenue with the engine still running. A red saloon-style BMW was parked in front.
On 6 May, just a few days before Mrs Patel-Nasri was killed, there was an attempted burglary at her house - police have not ruled out a link between that and the murder.
Scotland Yard have also confirmed her husband had been threatened earlier in the year in connection with his limousine business.
Mrs Nasri was a hairdresser by profession, but had been a special constable - a part time volunteer police officer - for three years.