But the hunt for Justyn's killers was hampered by a wall of silence as witnesses refused to name the gunman or give evidence in court. Detectives were also given a number of street names for the killer but could not establish a true identity.
Blackford, of Morville House, Wandsworth, was charged with murder in May last year, but prosecutor Jeremy Donne told the Old Bailey this week he could no longer resist a defence application to dismiss the case.
He told the court there were problems with the reliability of witnesses and the reliance on hearsay evidence and CCTV.
Detectives from Operation Trident have vowed to press on with their inquiries.
Speak to them on 020 8247 4543 or call Crimestoppers anonymously on 0800 555 111.