The man who died after being found unresponsive in police custody has been named by police as 43-year-old Taranaki Fuimaono from Westmere.
He died in Auckland Hospital following an arrest on Saturday evening.
Friends have been posting tributes on Facebook, expressing shock at his sudden passing.
"Still a shock are brudaz I was stunned as wen I gt told still am," wrote Moeroa Fasi Uleatuli.
"Rest In Love.... Brothas 4 Life and Grey Lynn Forever.... Love and Respect Uso," said Romeo Asiata.
Karyn Malthus, Auckland City District Commander said police have been providing support to his family.
A critical incident investigation is underway into the circumstances surrounding Fuimaono's death, Malthus said.
The matter has also been reported to the Independent Police Conduct Authority.
Malthus said the man had been treated at Auckland Hospital and discharged on Saturday.
Upon his discharge, he was arrested by police at the hospital just before 6pm and taken to the Auckland Custody Unit.
He was found by police unresponsive shortly after midnight.
An ambulance was called and police provided first aid, including performing CPR.
The Coroner and Worksafe NZ have also been notified.
A spokeswoman for Worksafe said it was in the process of making inquiries.
The Coroner confirmed the matter has been referred to Coroner Matthew Bates.
Fuimaono was charged with possession of methamphetamine on Saturday, the day before he died.
The Herald understands he was due to stand trial on serious drugs charges in relation to 3kg of methamphetamine on June 28.