A reward of £20,000 is being offered one-year on from the murder of Seun McMillan in north London.
The reward is available for information that leads to the identification, arrest and prosecution of those responsible for Seun's murder.
Detectives will return to the scene on the evening of Wednesday, 2 May to appeal to those with information that could identify the killer to come forward.
Seun [pronounced Shay-on], 23, was fatally stabbed following an incident in Cowper Gardens, N14 at around 19:15hrs of Tuesday, 2 May 2017.
A friend took him to hospital but Seun died there later that evening.
Detective Chief Inspector Simon Harding from the Homicide and Major Crime Command leads the investigation - he said:
"We believe Seun was the victim of a targeted attack by someone who had been tipped of that he was in the area.
"That means there was a specific element of planning in the events that led to this attack. I need to know who was involved in the chain of events that led to Seun's death.
"Seun was sitting with friends on a wall in Cowper Gardens when a number of people arrived at the scene in cars. Seun was stabbed and those involved fled the scene in those cars.
"There is now a significant reward on offer to anyone who can provide information that leads to the successful prosecution of those involved. I am convinced the answer lies within the local community.
"I would ask anyone with this information to ask themselves why they have not come forward. I urge the community to stand up for the community; stand up for Seun and his family and come forward."
Seun's mother Chantelle Bucknor is also appealing for information to help catch her son's attackers. She said:
"Seun was my first child, the big brother in the home - he was funny, loving and had a larger than life attractiveness. He was a person who his younger siblings loved and emulated his jovial, sensitive persona.
"I am pleading to parents, young people, the community - on the 2nd May 2017 our family's life changed forever. Seun was only 250 yards from the family home, when a tragedy occurred. He was killed, with one single stab wound to the heart and died on arrival to hospital.
"We as parents know each of our children, we know their friends, we know their moods, we know their comings and goings - There is a wall of silence and no one is talking although we know that there are witnesses.
"I am grieving but my pain is compounded when I see the loss in my other children's faces. I have an emptiness and numbness; there is a void in my life that will never be filled."
Anyone with information is asked to contact the incident room on 020 8721 4205, or police via 101 or by tweeting @MetCC.
To give information anonymously call Crimestoppers on 0800 555 111 or visit crimestoppers-uk.org.
= Six people have been arrested as part of this investigation.
Four of them - [A] a 27-year-old man; [B] a 25-year-old man; [C] a 20-year-old man and [D] a 19-year-old woman - have been released with no further action.
[E] a 27-year-old man on suspicion of conspiracy to murder has been released under investigation.
[F] a 20-year-old was charged with murder but the case was discontinued by the Crown Prosecution Service.