Met Police assistant commissioner Mark Rowley said:
Just to be clear, we are focused on the appeal on Crimewatch next week which we hope will produce new witnesses. It is clearly too early to speculate about where this will lead.
It remains vital for us, and the success of the appeal, that the public are focused on new facts that can be released by the investigative team rather than speculation.
I am impressed by what Detective Chief Inspector Redwood and his team have achieved but a conclusion is not imminent, there is much ground to cover and we still need assistance - hence the appeal next week.
More top news
Mild evening rounds off October ahead of cooler temperatures over the weekend.
Two families who lost men in military campaigns almost a century apart have made an emotional visit to the Tower of London's sea of poppies.
A British jihadi who has lost two of his brothers in Syria has told ITV News that he intends to stay and fight until he is also killed.