Police believe Anthony Morrison was at a wake when he was shot to death on Imperial Way around 5pm on June 19.
Officers and paramedics were called but Anthony was pronounced dead at the scene.
A man has since been charged with his murder, but detectives say more information is needed to understand what happened on that day.
Detective Chief Inspector Dan Whitten from the Specialist Crime Command, who is leading the investigation, said: “Our thoughts continue to be with Anthony’s family and friends at this difficult time.
“This charge marks significant progress in the investigation into Anthony’s death.
“However, it is vital that we further develop our understanding of what happened that day.
“We understand that Anthony was attending a wake at the time of the shooting, and we would implore anyone who was present in Imperial Way that evening, whether at the wake or otherwise, to contact us.
“Similarly we are keen to speak with anyone who attended a funeral service at New Testament Assembly in Tooting Bec and/or London Road Cemetery, Mitcham, earlier on June 19 and might have seen the victim.
“We are determined to get justice for Anthony’s family and friends, and we would ask for the public’s help in doing that by speaking to us or, if they’d prefer, anonymously to Crimestoppers.”
On June 23, 39-year-old Byron Cole, of Gleneldon Road, Lambeth was charged with murder.
He was due to appear at Bromley Magistrates’ Court on June 24.
A 37-year-old woman was arrested on suspicion of assisting an offender and was released on bail.
Detective Chief Superintendent Nick Blackburn, in charge of policing for Croydon, said: “I am very grateful to my Specialist Crime colleagues, who have worked tirelessly to investigate this matter professionally, securing charges.
“I’d now appeal to anyone who has any information to contact the team to help them with their investigation.
“I would like to reassure local communities and the wider public that firearm-enabled murders remain very rare in London.
“Our policing teams will continue to engage with communities across Croydon, providing extra support as required.”
Anyone who has video footage or any other relevant information is asked to contact us by visiting the Public Portal.
Alternatively, you can call 101 quoting CAD 6530/19Jun.
To remain anonymous, call the independent charity Crimestoppers on 0800 555 111 or visit crimestoppers-uk.org.
