Tetra Pak heir Hans Kristian Rausing is still not fit to be questioned about the death of his wife Eva, an inquest heard on Friday.
Police discovered the "lifeless body" of millionairess Mrs Rausing after they arrested her husband over drugs earlier this week, the hearing was told.
Mrs Rausing, one of Britain's richest women, was found dead in a bedroom of the opulent Cadogan Place house in London's Chelsea which she shared with Mr Rausing.
Friday's opening of the inquest into Mrs Rausing's death heard from Detective Inspector Sharon Marman, who told coroner Dr Shirley Radcliffe that Mr Rausing, 49, was stopped on suspicion of driving under the influence of alcohol or drugs on 9 July.
Officers found drugs in his car and when they searched the couple's home they discovered Mrs Rausing's body.
DI Marman said officers stopped Mr Rausing's car in Wandsworth where they searched it and discovered a small amount of drugs.
"Authority was granted to search the home address," she said.
"And during the course of that search officers discovered the apparently lifeless body of a female in one of the bedrooms."
She added of the suspect: "He has been arrested on suspicion of her murder and we await notification of when he will be fit to be interviewed."
Mr Rausing was arrested but is currently under medical supervision and detectives have been unable to interview him.
He was represented at the inquest opening at Westminster Coroner's Court by Neil Saunders QC, who represented 10 families at the inquest into the 7/7 bombings.
In 2008, Mr Rausing, heir to a £5.4 billion fortune from his Swedish father's business, was charged with drugs offences after police found crack cocaine, cocaine and heroin during a search of his home.
The couple were arrested in April that year after Mrs Rausing was caught with drugs as she tried to enter the US Embassy in London.
Court documents revealed that Mrs Rausing, then 44, was carrying about 10g of crack cocaine, 2.5g of heroin and 2.35g of diethylpropion, a banned stimulant and appetite suppressant.
A further drugs stash - 220mg of diazepam, used to treat anxiety - was also found in her Renault Clio car.
The couple's townhouse was subsequently searched. Officers found 5.63g of crack cocaine, 2.9g of heroin and almost 52g of cocaine.