Two people have appeared in court charged with possession of the drug MDMA for supply following the death of a 20-year-old Christchurch man.
But suppression orders mean they cannot be named.
The 20-year-old died on Sunday from what police have described as "a potential drug overdose".
A man and woman, both 33, appeared in the Christchurch District Court this morning charged with possession of a Class B drug for supply.
The woman was remanded on bail and the man will appear in court again this afternoon.
Their names were suppressed.
The man who died cannot yet be named publicly.
Family members were in court this morning and were visibly upset. They did not want to speak to media.
Detective Senior Sergeant Malcolm Inglis said inquiries into the fatality were ongoing.
"We cannot rule out the possibility of more serious charges," he said.
"Police would like to issue our deepest sympathies to the young man's family who are devastated by this loss."
Inglis said police were aware of several other MDMA-related incidents and issued a warning to anyone considering using the drug.
"Police have been made aware of security guards in Queenstown over the weekend assisting two people who had seizures after reportedly taking MDMA," he said.
"They didn't require medical treatment, but these incidents could have ended very differently.
"The best thing people can do to prevent any risk, is not to take illicit drugs.
"Police strongly recommend people take extreme care as what they think they may taking may, in fact, be a completely different drug or substance."
Inglis said police did not want to see anyone "becoming sick or worse" as a result of drug taking.
"If you or someone you know experience concerning or unexpected effects after taking something, please report it to High Alert, New Zealand's drug early warning system, at highalert.org.nz," he said.
"This is an anonymous function and helps keep others safe."
The 19-year-old disappeared without her wallet or mobile phone.