Tests have confirmed that the dog which killed a five-year-old girl on Merseyside was a prohibited pit bull terrier type.
Ellie Lawrenson died of severe head and neck injuries after being mauled at her grandmother's house in St Helens.
Ellie's family, who described her as "little angel", laid flowers outside the house on Tuesday night.
Police said post-mortem tests showed the dog was among the breeds prohibited by the Dangerous Dogs Act.
Two previous complaints had been made about the pet, which belonged to Ellie's uncle.
Supt Jon Ward, of Merseyside Police, said: "An assessment has been made by a recognised expert on the Dangerous Dogs Act, from the Metropolitan Police, and he has confirmed that the dog was a pit bull terrier type.
"The results of this post-mortem will now be included in the investigation and we will be speaking to all family members about the circumstances leading up to this tragedy.
"As soon as the investigation is completed, a report will be presented to the coroner and to the Crown Prosecution Service in terms of considering what offences, if any, have been committed."
Ellie was attacked in the early hours of Monday at the house in Knowles House Avenue in Eccleston.
She was staying with her grandmother, Jackie Simpson, while her mother and father went out to celebrate the New Year.
Ms Simpson, 45, tried to lock the dog outside, but suffered arm injuries. She has undergone surgery at Whiston Hospital.
Police have yet to speak to her about what happened.
The girl's family issued a statement in which they said: "Ellie was always happy and smiling.
"She was a little angel, full of life and always running around.
"We had a great Christmas together, with her little brother, Josh, who Ellie doted on and thought she was a second mother to.
"We are absolutely devastated and can't believe she is gone."
Members of the family laid tributes at the house, including one from her mother and father which read: "We are so broken hearted life will never be the same again, love Mummy and Daddy."
Merseyside Police said they were aware of two previous complaints about the dog.
They said a letter was sent to the owner when the dog bit another dog and a second when a complaint was made about noise.
It was shot dead by a police marksman following the attack.
The 1991 Dangerous Dogs Act imposed conditions on the ownership of four types of dog.
Lord Baker, who introduced the act when he was Home Secretary, said it was intended to get rid of pit bull terriers from the UK.