A 14-year-old boy has been arrested on suspicion of supplying Class A drugs following the death of Carson Price.
The 13-year-old, from Hengoed, died after being found unconscious in a park on Friday.
He was taken to University Hospital of Wales in Cardiff where he was pronounced dead.
Detective Chief Inspector Alun Davies, from Gwent Policesaid, "Specialist Gwent Police officers executed a warrant under the Misuse of Drugs Act, at an address in Pontllanfraith, Blackwood.
“A 14 year old boy from the area has now been arrested on suspicion of supplying Class A controlled drugs."
The 14-year-old who has been arrested is currently in custody at Newport Central Police Station.
Police said he will be interviewed with an appropriate adult as part of their investigation.
They also want anyone with any further information that may help them with enquiries to get in contact with Gwent Police and warned against any social media posts that "may jeopardise the investigation".