The dog that mauled a baby to death in Blackburn has been described as "very aggressive and dangerous" by a neighbour, who said the animal had previously entered his garden by breaking the fence.
Locals have claimed they reported dangerous dogs at the address of the killing to police.
Chief Superintendent Chris Bithell said Lancashire Police are making inquiries to see whether there have been previous issues with the dog, but that "at this moment it would be too early to speculate on that".
More top news
Mr Blavatnik, whose empire includes the Warner Music Group, has an estimated fortune of £13.17bn according to the Sunday Times Rich List.
Find out what to expect from the weather if you are running in the big race in London or watching from the sidelines.
It will be a soggy start to the weekend and temperatures will drop making it feel colder than in recent days.