Hallam's mother, brother and sister were all in court to witness the culmination of their seven-year battle to bring him home.
But his father, Terry Hallam, 53, committed suicide 15 months ago, unable to cope with the stress of his son's continued incarceration.
"My dad should be here to see this," reflected Sam's brother, Terry Hallam jnr, 32. "I want to take Sam with his brother and sister to see his father's grave for the first time together."
Sam Hallam said: "Words can't describe how I feel. I'm just going to spend time with my family and take every day as it comes. I've been in prison for seven years, it's all I've known in that time. Without this support I would not have made it."
He was convicted of murdering Kassahun, who died from head injuries after being beaten by a gang of youths on a housing estate in Clerkenwell in October 2004.
Ethiopian-born Kassahun's attackers used a screw-studded baseball bat.
Hallam, who was only 17 at the time, always maintained that not only was he not a member of the gang, but that he was playing football with a friend a kilometre away when the murder happened.
He was sentenced to life at the Old Bailey in 2005 when he was 18 years old. He was convicted despite no forensic evidence or CCTV footage linking him to the attack.
The first appeal failed in 2007 but fresh evidence gathered by campaigners, including Paul May, who had played a central role in the campaign to free the Birmingham Six, persuaded the Criminal Case Review Commission to look at the case. The actor Ray Winston, a distant relative, was also among the campaigners.
The CCRC ordered Thames Valley Police to help it reinvestigate the case originally handled by Scotland Yard, led by Detective Chief Inspector Michael Broster.
The Thames Valley investigation found major failings in the way the first investigation had been carried out, specifically the failure to pursue reasonable lines of inquiry and the failure of Broster to record his investigative decision-making.
Hallam's barrister, Henry Blaxland, QC, told Hallett, Justice Openshaw and Justice Spencer: "It is our case that this appellant Sam Hallam has been the victim of a serious miscarriage of justice brought about by a combination of manifestly unreliable identification evidence, the apparent failure of his own alibi, failure by police properly to investigate his alibi and non-disclosure by the prosecution of material that could have supported his case."
- Independent
