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
The five living former US presidents appeared together for the first time since 2013 to raise money for hurricane victims.
Some 465 seats are up for grabs in the lower house, which Abe dissolved last month to call a snap election amid rising approval ratings.
Ministers are also looking at schemes such as “lock-in agreements” to reduce the 250,000 sales that fall through annually.