Police have issued an urgent appeal to trace the man believed to have owned a Belgian mastiff that mauled a woman to death.
The victim, named locally as Barbara Williams, was savaged last night at a house on Demesne Road, Wallington, south London.
The dog, described by one officer as large and ferocious, was shot dead by police marksmen.
Police said today they were urgently seeking Alex Blackburn-Smith, who is believed to be the owner of the dog.
Detective Chief Superintendent Guy Ferguson: "We are in the process of contacting the lady's next-of-kin. We also urgently want to speak to Alex Blackburn-Smith, who is the main occupier of the premises, in relation to the circumstances of the incident to establish facts."
Mr Ferguson described the dog as "distinctly large" and said at the time of the attack another woman of similar age to Ms Williams was in the house with a child under five.
"It was a very ferocious dog," he said.
"The officers had to use shields to contain the dog."
He said police would be investigating previous complaints about the dog and what, if anything, was done.
On Mr Blackburn-Smith, he said: "My information is he lives at that address and has a 1976 date of birth and we are making inquiries to speak to him."
On the victim, Mr Ferguson said: "I believe she is a lodger at the premises which are controlled by him."
Next door neighbour Burhan Yanbolu said the attack was "always going to happen".
Mr Yanbolu, a minicab driver, had previously called the police and council to complain about the animal after it smashed their adjoining fence.
He said: "It was going to happen, it was always going to happen.
"I once saw the young boy in the house playing with the mastiff and it was getting too rough, so I told the woman who got killed, and she said they were just playing."
Mr Yanbolu, a father of twin girls, said: "We didn't have anything to do with them because of the dog.
"It was a big strong dog.
"We started having problems with them in autumn 2009.
"There were two dogs and the big one would lean against the fence and could see over it on its hind legs.
"We had concerns it would get over and could get in our garden."
Mr Yanbolu said he complained about the dog to Mr Blackburn-Smith.
"This has come as no surprise to us at all," he said.
"Last year our children couldn't play in the garden at all because the mastiff damaged a big chunk of fence crashing through."
He said the dog managed to break free on a few occasions and another woman who lived at the house with Ms Williams was too frightened to try to tie it up.
He said: "The lady who lives upstairs said she was too scared and would have to get Alex, who works in a security job, home to do it."
Describing last night's horrific events, Mr Yanbolu said: "The police came through our garden to get access.
"We could hear them talking about the female, saying she was badly injured and there was lots of blood, but they couldn't get in to secure the dog.
"Somehow the dog went into a different bit and the police and paramedics worked on the lady."
He said police marksmen evacuated neighbours on the other side and considered moving him and his wife as well.
"They told us to expect 10 rounds to take the dog out," said Mr Yanbolu.
"But it was only four. We heard three and then 30 seconds later there was one more."
Sutton Council confirmed it had received a complaint about dogs damaging a neighbour's fence last year.
"The council and the police's Safer Neighbourhood Team were contacted in connection with another smaller dog and damage to a fence at this address in August 2009," said councillor Colin Hall, responsible for dog control.
"At that point there were no legal grounds for the council to intervene on the basis of our statutory powers.
"There were no subsequent complaints."