Azezur Khan, known as Ronnie, had just left the service of his school friend in East Dulwich and was making his way to the burial when he was gunned down at around 3pm.
The Metropolitan Police said he was hit a number of times in an exchange of gunfire between Rocknells Place and Forest Hill Road.
A fresh appeal comes just days before the second anniversary of his death on November 3.
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A bright and sunny day tomorrow, but feeling distinctly cool and chilly tonight.
An ITV News London investigation has discovered the inquest will now be held at Westminster Coroner's Court.
The family court finalised the adoption as the criminal proceedings were still under way. The couple have vowed to fight for their child.