Gwent Police were called to an address in Pentwyn, Penyrhoel, Caerphilly at around 3.55pm on Monday 8 November, following reports of a dog attack.
Officers attended, including specially-trained firearms officers, alongside paramedics from the Welsh Ambulance Service, who confirmed that a 10-year-old boy had died at the scene.
He has been named as Jack Lis.
A 28-year-old woman from the Caerphilly area was arrested on suspicion of being in charge of a dog dangerously out of control causing injury resulting in death. She was later released on conditional bail.
Two men – a 34-year-old from the Mountain Ash area and a 19-year-old from the Caerphilly area – attended voluntarily in relation to an offence of being in charge of a dog dangerously out of control causing injury resulting in death. Both were later released.
Chief Superintendent Mark Hobrough said:
“As our investigation continues, we will be removing our scenes from the area and the work to identify the breed of dog involved is also progressing.
“As we’ve arrested an individual on suspicion of an offence linked to the attack, and spoken to two others voluntarily, we’re looking to identify where any criminal matters have occurred.
“I understand that there is a lot of interest about this in our communities.
“It is vital that people are considering the tone and language used in comments posted on social media about the identities of anyone involved in this matter as part of our enquiries.
“As this is a live investigation such comments may have impact on our ability to bring anyone found to have committed a criminal offence to justice.”
Anyone with information is asked to call Gwent Police on 101, quoting log reference 2100392510.
You can also send police a direct message on Facebook or Twitter. Alternatively, you can contact Crimestoppers anonymously by calling 0800 555 111.