The "dangerous" dog that mauled an 11-month-old baby to death was a banned breed, police have said.
Ava-Jayne Corless was asleep in bed at a house in Blackburn on Monday night when she was savaged by the pit bull terrier.
Police said the dog, which was destroyed after the attack, had been identified by experts as a pit bull terrier-type dog which people are prohibited from owning under Section 1 of the Dangerous Dogs Act 1991.
Locals claim to have made previous complaints to police about the dog's behaviour.
It was also reported that the RSPCA had been called to the house after claims that a neighbour’s cat had been killed, but the charity concluded it was an accident.
The girl's mother, Chloe King, 20, and her partner, Lee Wright, 26, were held on suspicion of manslaughter. The couple have now been released on bail pending further inquiries, police said.
King and Wright were said to be downstairs when the attack took place, while Ava-Jayne was in a front bedroom.
Police and ambulance staff attempted to resuscitate Ava-Jayne at the address in Emily Street but she was pronounced dead at Royal Blackburn Hospital a short time later.
Ava-Jayne’s father, named as Dean Corless, 24, last night paid tribute to his "beautiful little girl."
"I am absolutely devastated," he said. "She was the most beautiful and adorable little girl, she was just the best. She was my whole world.
"I will miss her every single day, I just don’t know what to do now."
Lancashire Police have said they are checking "whether there have been previous issues with this particular dog."