Two dogs that attacked and killed 68-year-old Esther Martin in Essex were XL bullies, police have confirmed.
She was visiting her grandson, 11, at a home in Jaywick, near Clacton-on-Sea, on Saturday when she was attacked.
Essex Police said post-mortem examinations carried out on the dogs, which were destroyed, confirmed they were XL bullies.
Ashley Warren, 39, was arrested on suspicion of dangerous dog offences and released on police bail until March.
Ms Martin's daughter, Sonia Martin, previously told the BBC her mother, from Woodford Green in north-east London, was told by the dogs' owner to intervene with a broom when puppies in the house began fighting.
It was believed she was attacked inside the property on Hillman Avenue, just off the seafront in the coastal village.
Ch Supt Stuart Weaver said: "I know there has been a huge amount of speculation about the breed and type of dog involved here, but it was really important we got that information right and established the facts.
"We owe it to Esther and her family to ensure we are thorough, professional and, above all, fair.
"XL bully is not a breed of dog in itself, but a sub-category of the American bully, and identifying categories of a breed can be a complex process."
Essex Police said as well as the post-mortem examinations on the dogs an expert was brought in to examine their physical features - all of which were used to conclude the pets were XL bullies.
Ms Martin's family previously said they were angry at the conditions the animals were kept in.
"People complain [about] the dogs; it's not the dogs," said Sonia.
Ms Martin said the family believed the pets, two adults and puppies, were unregistered XL bully dogs which had been "kept penned in a small chalet".
"How the hell can that be any good for an animal?" said Ms Martin.
Ms Martin's family previously said she was "getting her life back together" following the death of one of her daughters.
Mr Warren was the partner of Esther Martin's late daughter, who died about two years ago.
Sonia Martin said that during the fatal attack her nephew "ran out of the house screaming for help" and said some neighbours grabbed spades to try to "fight off" the dogs.
"We'd really like to thank all the neighbours for coming and helping and trying to save my mum's life," she added.
"My concern was if my nephew hadn't run out of the house what could have then happened to him?"
Neighbours had described hearing "screaming".
Ch Supt Weaver reiterated his thanks to members of the public who "bravely tried to save Esther before our officers arrived on scene".
"What you did was hugely courageous and a reflection of the values of the community of Jaywick," he said.
"I also want to again praise the unflinching bravery and professionalism of the officers who attended and whose actions ensured the community was safe."
What are XL bully dogs and what is the law?
An XL bully is the largest kind of American bully dog. Other types include standard, pocket and classic.
The government described them as large dogs "with a muscular body and blocky head, suggesting great strength and power for [their] size".
In England and Wales, the breed has been added to the list of dogs banned under the Dangerous Dogs Act 1991. It means breeding, selling or abandoning them is illegal.
Certificate of Exemption, allowing owners to keep their XL bullies, can no longer be applied for, and the government guidance says owners without a certificate should contact their local police force.
Dogs covered by a certificate must be kept on a lead and muzzled in public.
Scotland has also announced a ban, which will come into force later in the year.