Officers investigating a fatal pit bull terrier attack on a five-year-old girl are yet to question a key witness or arrest the dog's owner, police said.

Ellie Lawrenson was killed by the animal in the early hours of New Year's Day while staying at her grandmother's home in St Helens, Merseyside.

Her grandmother, 46-year-old Jackie Simpson, battled to stop the attack and suffered arm injuries which required emergency surgery. She remains in hospital and was said to be too traumatised to speak about the incident.

A Merseyside Police spokeswoman said: "She is still severely traumatised and officers have not been able to speak to her yet. That situation is unlikely to change ..."

A view of the house in St Helens where Ellie Lawrenson died after being mauled by a dog Full Image

The spokeswoman described Mrs Simpson as a "key witness" to the attack but insisted the investigation was not being hampered by the delay in speaking to her.

The force also confirmed that no arrests have been made, despite the dog being confirmed as a "pit bull terrier type". Owning pit bull terriers is illegal under the 1991 Dangerous Dogs Act, and carries a maximum punishment of six months in jail or a £5,000 fine.

Asked about the apparent delay in making an arrest, the spokeswoman said: "We are in the process of ascertaining precisely who is the dog's owner." The dog which attacked Ellie was understood to belong to her uncle, Kiel Simpson, who lived at the house.

Police said they believed "Ellie's uncle" was the owner on the day of the attack, and St Helens Borough Council sent two warning letters to Mr Simpson after the pit bull terrier attacked another dog and caused a nuisance with his barking.

Neighbours also saw Mr Simpson, who has a previous conviction for drug dealing, as the owner.

The one-year-old dog, named Reuben, was shot dead by police at the scene of the tragedy.