David Hockney's assistant died as a result of misadventure when he drank acid after taking a range of drugs, a coroner has ruled.
Dominic Elliott, 23, died after drinking household drain cleaner at the artist's home in Bridlington, East Yorkshire, in March.
A two-day inquest in Hull heard he drank the liquid after "partying" with his partner John Fitzherbert, 48.
Humberside Police confirmed it was investigating possible drugs offences.
After the verdict, a police spokesman said a 48-year-old man and a 23-year-old man had been arrested on suspicion of drugs offences and remained on bail as inquiries continued.
He said no one had been charged.
'No suspicious circumstances'
Mr Fitzherbert was Mr Hockney's partner for 20 years and still lives at the artist's home and runs his domestic affairs.
The court was told Mr Elliott drank the acid, which caused serious damage to his mouth and throat before perforating his stomach, after taking cocaine and ecstasy. He had also consumed alcohol and cannabis before drinking the liquid, the inquest heard.
Bradford-born artist Mr Hockney was in bed asleep at the time and was "completely unaware" of what had happened, the inquest heard.
The coroner, Professor Paul Marks said there was "not a shred of evidence Dominic intended to take his own life".
He said there were no suspicious circumstances or any "third party" involvement in the death.
The coroner said he recorded a verdict of misadventure on the basis that Mr Elliott took the substances he did in the expectation that there was a risk involved.
Hull Coroners Court heard Mr Elliott died in the early hours of 17 March after Mr Fitzherbert took him to hospital in Scarborough.
Drugs evidence cleared
The coroner said it was one of the "enigmas" of the case that Mr Elliott appeared not to be showing any signs of pain despite a pathologist saying the ingestion of the acid would have caused extreme agony.
He said it was possible the drugs Mr Elliott had taken lessened the pain.
By the time he arrived at Scarborough Hospital he was completely unresponsive.
Det Sgt Thomas Napier, who compiled the file on the death for Humberside Police, told the coroner: "It does remain a mystery - for an intelligent young man to drink such a noxious substance."
Mr Hockney's chief assistant, Jean Pierre Goncalves De Lima, told the inquest he received a phone call from Mr Fitzherbert after Mr Elliott's death, asking him to clear his room of "any evidence of drug use".
Mr Goncalves De Lima said he did clear Mr Fitzherbert's room but later told police what he had done.
'Hockney 99% deaf'
Asked why, he said Mr Hockney had suffered a mini-stroke last year and he was worried about the effect of this kind of "exposure" on his boss's health.
He also said Mr Hockney was 99% deaf without his hearing aids.
Mr Goncalves De Lima said he was aware of some drug use in the house but added that Mr Hockney was not aware of this.
The coroner said he believed Mr Hockney, who shares his house with three other men including Mr Fitzherbert, was unaware some of the occupants of his home were abusing illegal drugs.
The court was told that Mr Elliott suffered bouts of depression and was deeply affected by the death of his twin sister at birth and his father, when he was 11.
Mr Fitzherbert went missing two days after Mr Elliott's death, but was later found at a Bridlington beauty spot and taken to hospital. He later booked himself into the Priory Hospital in London, the inquest heard.