A Worthing man may have died after taking drugs cut with an unknown and potentially poisonous substance, an inquest heard.
At 6.27am on June 15, Neil Woods was found unresponsive in the bath at the hostel where he lived in Cortis Avenue, Broadwater.
He had no pulse and was in cardiac arrest, but his heart was restarted by paramedics half an hour later and he was rushed to Worthing Hospital.
The 44-year-old never regained consciousness and died in hospital three days later on June 18.
Toxicology reports on Mr Woods' body showed he had traces of methadone, cannabis, morphine - which is closely associated with heroin - and by-products of cocaine in his system.
There was also a chemical compound in his body which was not recognised by the tests.
At the inquest into Mr Woods' death on Tuesday, assistant coroner Christopher Wilkinson said it was possible this unknown substance could have been a contributing factor.
He said: "His heroin could have been cut with something unidentified.
"That in itself could have caused his body to fail. It may have been a poison or contaminant that caused him to die."
The inquest heard how Mr Woods was underweight and had been taking drugs on and off for many years, but moved on to injecting heroin four or five years ago.
A recent needle wound was found on his body when he arrived at Worthing Hospital, which suggested he had taken drugs shortly before his death - but the low levels in his system did not reflect this.
Another theory put forward by Mr Wilkinson about how Mr Woods may have died was that his tolerance to drugs had slipped due to a period of abstinence, which meant a low dose was enough to send him into cardiac arrest.
Coroner's officer Geoff Charnock suggested that habitual cocaine use in his past could have weakened his heart, precipitating the heart attack.
The cause of death was not established by a post-mortem examination held at Worthing Hospital on June 21.
Mr Wilkinson concluded that Mr Woods’ death was drug related.