Five men were jailed for life over the murder 16-year-old Hani Abou El Kheir, who was stabbed to death in Pimlico last January.
The teenager was assaulted with weapons including swords, a meat cleaver, knives and a Taser stun gun.
Hani Abou El Kheir was stabbed more than 20 times while walking through an estate in Pimlico.
The family of Gareth Williams, who was found dead in a holdall, have said the unknown circumstances of his death "adds to their grief".
Police said it had concluded that spy Gareth Williams probably died alone in an accident, but admitted there was no evidence to establish the circumstances of his death "beyond all reasonable doubt".
The family statement read: "We are naturally disappointed that it is still not possible to state with certainty how Gareth died and the fact that the circumstances of his death are still unknown adds to our grief.
"We consider that on the basis of the facts known at present the Coroner's verdict accurately reflects the circumstances of Gareth's death. "
The family said they remain disappointed that Gareth William's employers at MI6 failed to make inquiries into his welfare when he failed to attend work in the days before his body was found.
Deputy Assistant Commissioner Martin Hewitt, of the Metropolitan Police, says there remains "gaps in understanding" regarding the death of MI6 worker Gareth Williams.
But he has concluded, following two years of investigation, that it is "most probable" that the codebreaker was alone at the time of his death.
The family of Gareth Williams's family said they were "naturally disappointed" by the conclusions of the Met Police, and said they still believe he was killed.
Gareth Williams was found in a bag in the bath at his flat in Pimlico in 2010. Pathologists said he would have suffocated within three minutes if he was alive when he got inside the holdall. None of his DNA was found on the lock on the bag and his palm prints were not found on the rim of the bath.
Spy Gareth Williams, whose body was found in a holdall in Pimlico, probably died alone in an accident. Met Police said today they disagree with the conclusion of a coroner last year that the codebreaker was probably killed unlawfully.
Deputy Assistant Commissioner Martin Hewitt said: "With the conclusion of the investigation, the Metropolitan Police's position is that, on balance, it is a more probable conclusion that there was no other person present when Gareth died.
"But the reality is that for both hypotheses there exist evidential contradictions and gaps in our understanding."
The full message on the school's website from Dr J J Saxton, director of education at Future Academies, said:
I am writing to let you know that having successfully set up and opened Pimlico Primary, Annaliese Briggs has decided to leave Future Academies to pursue other opportunities within primary education.
A new principal of Pimlico Primary has been appointed. Coming from within the group, our new principal is already known to you and your children, and brings over 10 years experience in both early years and leadership.
We are delighted that Annaliese will continue to support Pimlico Primary as it grows by becoming a governor.
Annaliese Briggs used to work on education reform and the curriculum for the Civitas think tank, and studied English at Queen Mary, University of London. She was controversially appointed as head of the central London school in March.
- It is believed that at the time she had no formal teaching qualifications, but spent time working in primary schools in Wandsworth
- Pimlico Primary, which began admitting pupils for the first time last month, is sponsored by Future, a charity set up by Lord Nash - a minister in the Dept for Education
A headteacher appointed to run a free school despite having little experience or teaching qualifications has left the job just weeks after it opened. Annaliese Briggs is leaving "to pursue other opportunities within primary education", according to a notice to parents on Pimlico Primary's website.
The Health and Safety Executive is investigating the explosion which happened on Pimlico Road in central London, yesterday morning.
– Health and Safety Executive
"We are aware of this and we are making inquiries into what happened."
– UK Power Networks
"Safety is our top priority and the cause of this incident is being investigated. We apologise to customers for the inconvenience caused by the power cut and our staff restored all supplies as quickly and safely as possible."