A drug dealer who used the dark web to supply customers - including four that later died - with the powerful synthetic opiod fentanyl has been jailed for eight years.
Kyle Enos, 25, of Newport, south Wales, sold the drug to 168 people in the UK, Europe and the US between May 2016 and May 2017.
Cardiff Crown Court heard that following his arrest, police went through Enos's customer database due to the "potentially lethal effects" of fentanyl.
Four people on his database had died but it cannot be proven that the fentanyl supplied by Enos was related to their deaths.
The court heard Jonathon Robinson, 25, from Northumbria, was found dead at home, while university student Jack Barton, 23, died in Cardiff in January 2017.
Aaron Rees, 34, from Ammanford in Carmarthenshire, Wales, was found dead last March. The fourth person, who was not named in court, died in Scotland.
Sentencing Enos, judge Eleri Rees, the Recorder of Cardiff, told him: "It is 25 times more powerful than heroin as is evidenced by the deaths of at least four young people who were your customers.
"None of those deaths can be attributed to fentanyl supplied by you but it is evidence of how dangerous a drug it is."
Enos admitted importing, supplying and exporting fentanyl in August last year.
The judge said the delay in sentencing Enos was to consider whether further charges would arise from the deaths of four of his customers, as well as to obtain more information about the effect of fentanyl.
Charges will not be brought against Enos for the deaths that occurred in England and Wales, but investigations are continuing in Scotland.