Det Ch Insp Rebecca Woodsford said: “Tottenham’s tight knit community has experienced the heartbreaking impact of gun crime.
“There is someone out there who knows what happened that night and we are urging those individuals to find it in their heart to come forward.
“No matter how small you think the information is, please speak to us. It could be exactly what we need to locate those responsible.”
Crimestoppers is offering the reward for any information which the charity exclusively receives and leads to the conviction of those responsible.
Mr Mohammed’s sister said her brother, who had a son, deserved justice.
“To stay silent is to be complicit,” she said. “To stay silent is to let a grieving mother suffer in confusion. To stay silent is to let a little boy grow up not knowing what happened to his father.”
Four men were arrested on suspicion of murder in March and April. They were questioned and released on bail pending further investigations.
The police investigation continues.