£40k reward over 40-year-old lido death in Hampstead
Cold case detectives investigating the death of a 15-year-old boy more than 40 years ago are offering a £20,000 reward for information.
Enrico Sidoli died in hospital on 19 July 1976, 11 days after being pulled unconscious from the lido in Parliament Hill, Hampstead.
Witnesses said he had argued at the open-air pool with a group of boys.
A member of Enrico's family has offered to match the reward with a further £20,000.
The teenager had gone to the pool on 8 July 1976 with his sister and her children.
He was said to have argued with the boys before being assaulted and thrown into the pool.
Detectives believe he may have been held underwater for a period of time.
A post mortem gave his cause of death as irreversible brain damage caused by cardiac arrest.
Iolanda Sidoli, Enrico's sister, said the pain of losing him "has never gone".
"I remember crying uncontrollably. I was a child whose heart was broken and have never really recovered from the loss," she added.
"When Enrico died, we all died. Our mother and father suffered terribly. Our mother never recovered from his terrible death, spending days and nights by his grave.
"But the worse thing is how Enrico must have suffered at the hands of the cruel people who took his life."
Since the death, police have taken more than 1,100 witness accounts and launched public appeals for information.
Two people have been interviewed under caution.
A 16-year-old boy was interviewed by officers in September 1976 and a 25-year-old man in August 1986. No further action was taken and there have been no arrests or charges.
Cold case detectives are now revisiting the investigation in a fresh bid to find out what happened that day.
They want to trace and speak to a potential key witness, including a man that can be seen in a picture taken moments after Enrico was recovered from the water.
A £20,000 reward for information leading to the arrest and conviction of the person responsible for Enrico's death is being offered and a member of his family has offered to match it.
Det Insp Susan Stansfield, of the Met's Special Casework Investigation Team, said: "I hope that after 41 years, any witnesses who were too scared of, or had loyalties to, the people involved at the time will now find the courage to contact police."