Investigators are looking into whether a dog that mauled a young boy to death was a breed that is banned in the UK.
Jack Lis, 10, was killed at the home of a friend in Pentwyn, Penyrheol, on Monday.
Gwent Police said on Wednesday they had arrested a woman on suspicion of being in charge of a dog dangerously out of control causing injury resulting in death.
The dog was shot by firearms officers who also attended the scene.
Two men voluntarily attended the police station in relation to the offence.
A 34-year-old from the Mountain Ash area and a 19-year-old from the Caerphilly area were later released.
The case has sparked calls for a review of the laws around keeping dangerous pets. Wayne David, the Labour MP for Caerphilly, said: “There needs to be an examination of the Dangerous Dogs Act to see if the law needs to be strengthened."
Chief Superintendent Mark Hobrough said work was continuing to identify the breed of the dog. Neighbours said the dog resembled an American pit bull - also known as a pit bull terrier - which is one of four dog breeds that are banned in the UK.
What dog breeds are banned in the UK?
There are four dog breeds that are illegal to own:
Pit bull terrier
While the breeds themselves are banned, there are also activities associated with them that are illegal in the UK.
Under the guidelines of the Dangerous Dogs Act, that came into effect in 1991, anyone who owns – or sells, abandons, gives away or breed from – an illegal breed faces punishment.
The maximum punishment could be up to six months in prison or an unlimited fine or both, while community orders can also be handed out, depending on the perceived risk factor to the public.
The dogs will also be destroyed.
Anyone with a banned dog can have it removed by the police or local council, even if there has been no complaints and the dog is not acting dangerously.
Police can also seize a banned dog without a warrant if seen in a public place – experts will then determine if the animal is an illegal breed.
Courts can determine that a banned dog is not a danger to the public and will allow an owner to keep it if put on the Index of Exempted Dogs (IED).
However, the dog must be neutered, microchipped, kept on a lead and muzzled at all times when in public and kept in a secure place so it cannot escape.
Owners must be over 16 and also take out insurance against the dog injuring other people, while the certificate of exemption must be shown to police or council dog wardens when asked.
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