Police are still awaiting the results of toxicology tests over the death of a young father of two in Batley.
Jordan Jubb, 22, collapsed in Bradford Road at 4.30am on Sunday.
Police said Mr Jubb and two other men showed “overdose symptoms” and enquiries are underway as to what substances they may have taken.
Police issued a warning about taking drugs saying there was no “safe way” to take drugs.
Det Insp Stef Wiseman, of Kirklees CID, said the results of a post-mortem examination were still awaited.
Mr Jubb and another man, aged 24, were taken ill in Bradford Road and a taxi driver is believed to have raised the alarm.
The men were taken to hospital where Mr Jubb died later. A third man, aged 19, went to hospital two hours later with similar symptoms.
Mr Jubb had earlier been in the TBC nightclub in Bradford Road. TBC opened in August by the company which previously ran the Frontier club.
The Frontier, formerly Batley Variety Club , closed in July.
A spokesman for TBC – which stands for Terrace Bar Club – said staff were helping police with their enquiries.
Mr Jubb’s mother Debbie said her son was not a drug user and was well educated about drugs. Friends have paid tributes on social media.