Two men were arrested on Wednesday, 4 May, by officers investigating the fatal stabbing of Adeniyi Lateef Shode (known as Aden or Enda) in Northolt in 2011.
The 23-year-old man [E] and 24-year-old man [F] were arrested on suspicion of murder at addresses in north London. Both have been bailed to return, pending further enquiries, on dates in mid-June.
Officers continue to appeal for witnesses and information and are offering a reward of up to £20,000 for information leading to the identification, arrest and prosecution of the person or persons responsible.
Adeniyi, of Edgware, was discovered collapsed close to the junction of Rowdell Road, Ealing Road, and Kensington Road, at approximately 20:50hrs on 2 May 2011.
He had suffered stab injuries. He was taken to St Mary's Hospital and died of his injuries later that night.
His mother Antonia Francis said in an earlier appeal: "All our family thinks about Aden every day. We remember his laugh and smile and he always remains in our thoughts.
"It still hurts us to think that whoever killed Aden is still out there and we pray that it doesn't happen to anyone else's family.
"I would ask anyone who may be able to help us to speak to the police. If you are not happy talking to the police then please tell someone and get them to pass the information on. What is important is that the police can track down whoever took my son from us."
Detective Inspector Garry Moncrieff, from the Homicide and Major Crime Command, said: "Although five years have passed, officers remain committed to bringing Aden's killers to justice.
"Allegiances may have changed over this time and those who may know who is responsible for Aden's death may not have the same sense of duty to those involved. We strongly believe that people out there may know who murdered Aden and why.
"Anyone with any detail, no matter how minor, is urged to contact police. It may provide closure to Aden's family who want to see justice done."
Anyone with information is asked to call the Incident Room at Hendon on 020 8358 0300; if you wish to remain anonymous call Crimestoppers on 0800 555 111.
+ Two men (A, D) and two womaen (B, C) were arrested in May 2011 and subsequently released with no further action. Nobody has ever been charged with Aden's murder.