Detectives have confirmed a fourth man arrested by police investigating the murder of father-of-three Redwan El-Ghaidouni in Hillingdon has been bailed.
The 36-year-old man was arrested on May 13, on suspicion of conspiracy to murder. He has since been bailed pending further enquiries to a date in mid-June.
Three people - a 41-year-old man, a 29-year-old man and a 34-year-old woman - who were arrested on conspiracy to murder on Wednesday, 11 May have been bailed, pending further enquiries, to dates in early June.
A £50,000 reward remains on offer for information leading to the arrest and prosecution of the person or people responsible for Redwan's murder.
Redwan was fatally shot as he sat in the driver's seat of his car on the driveway of the home he shared with his partner and three children just before 19:00hrs on Tuesday, 3 February 2015.
After Redwan pulled into his driveway, he was approached by a man who shot him multiple times through the car window.
The suspect ran off through an alleyway that leads to Saunders Road. He turned the corner where he was caught on a CCTV camera before running in the direction of Dowding Road.
He was wearing a distinctive dark hooded top with a large logo on the front as well as dark bottoms, dark gloves and dark shoes or trainers.
CCTV also shows the suspect - again wearing the top with the large motif - in Saunders Road on numerous occasions on Saturday, 31 January and Monday, 2 February. It is thought these were failed attempts to shoot Redwan.
Officers are also still keen to hear from anyone who can identify a man seen an hour before Redwan was murdered, at about 18:00hrs, standing on the verge by a telegraph pole at the junction of St Andrews Road and Vine Lane.
This is opposite Redwan's house.
Anyone with any information is asked to call the incident room on 020 8785 8099 or Crimestoppers anonymously on 0800 555 111 or via crimestoppers-uk.org.