Police say the death of a 19-year-old man from Leabrooks on Saturday could be linked to fake ecstasy pills.
Officers were called to an address on Chapel Street at around 11.20pm by the ambulance service who were treating the man.
He was taken to hospital where he was later pronounced dead.
A police spokesperson said: “The death is being investigated as being related to the taking of so called ecstasy tablets.
“Initial tests on tablets recovered indicate that they do not contain any genuine ecstasy (MDMA) however further tests will be required to find the exact ingredients.”
A 16-year-old boy and an 18-year-old woman have been arrested in connection with supplying drugs. They have been released on bail pending further inquiries.
Various other people have been spoken to in connection with the investigation.
The spokesperson continued: “Derbyshire police want to take this opportunity to warn again about the dangers of taking illegal drugs, which can have tragically fatal consequences.
“Users of drugs should also be aware that the drug they buy may not contain what they are expecting.”
For further information on the dangers of drug taking, head to the FRANK website, or www.doyouknowwhatsinit.org.uk, which contains details of the different substances found locally.
Anybody with information about the supply of illegal drugs should ring their local police on 101 or Crimestoppers on 0800 555 111.