The charity Crimestoppers has upped its reward in the search for Temitope Adeyinka, a.k.a "Limo" 38, also from Newham.
A Nigerian man has been declared wanted in the UK.
This is as the UK police announced an increased reward of £10,000 for anyone that will help in the arrest of the Nigerian wanted for the death of a 50-year-old man at a party.
Robert Powell was shot multiple times in Roydon, Essex, on 13 June 2020.
Israar Shah, 38, from Brentwood, and Nana Oppong, 42, from Newham, have been arrested on suspicion of murder in recent months.
The charity Crimestoppers has upped its reward in the search for Temitope Adeyinka, a.k.a "Limo" 38, also from Newham.
Det Sup Stephen Jennings, of Essex Police, said: "There's a loving family, a mother, children, grandchildren, who have spent more than two-and-a-half years in a state of limbo and grief. "They need and deserve answers."
Mr Powell, a father-of-three and grandfather-of-two, was fatally wounded outside a house party in Water Lane in the early hours of the morning.
Two women received single gunshot wounds in the incident.
Police said Mr Oppong, who previously lived in West Road in Newham, was detained trying to enter Morocco from Spain in September last year.
He was later arrested on suspicion of murder, possession of a firearm with intent to endanger life and wounding without intent, and is due to be extradited to the UK.
Essex Police said Mr Shah had been located in Spain and extradited into UK custody. He is due to appear at Chelmsford Crown Court charged with murder on 12 June.
Police said the third suspect Mr Adeyinka, also known as Limo, was subject to a European Arrest Warrant.The force said he was about 5ft 8ins tall (1.7m) and of medium build.
Anyone who knows the whereabouts of Temitope Adeyinka (a.k.a Limo) is asked to call 999 immediately.