Eva Rausing, one of Britain's richest women, was found dead at her London home last night as her husband, the Tetra Pak drinks carton heir Hans Kristian Rausing, was being questioned by police.
Ms Rausing, 48, had a history of drug problems. Her body was discovered after Mr Rausing, 49, was arrested in possession of drugs in south London on Monday. When police searched the couple's home in Cadogan Place in Belgravia later, they found Ms Rausing's body in an upstairs room.
A spokesman for the Metropolitan Police said: "On Monday, a 49-year-old man was arrested on suspicion of possession of drugs. Following a subsequent search of an address in Cadogan Place a body was found." He added the death was being treated as "unexplained".
The couple, who had other homes in Barbados and on a luxury cruise liner, have been dogged by drug addiction throughout their adult lives. They met in a rehab clinic in America while they were still in their 20s.
Mr Rausing stands to inherit the £5.4bn Tetra Pak business enterprise built by his Swedish father. He and his American-born wife, who have four children, had a run-in with the law in 2008 when Ms Rausing was arrested for trying to smuggle drugs into a party in the US embassy in London.
A later search of their house turned up £2,000 of heroin and crack cocaine. However, the couple were never prosecuted and were instead handed a "conditional caution" after agreeing to treatment for addiction.
"I have made a serious mistake which I very much regret," Ms Rausing said at the time. "I intend to leave as soon as possible to seek the help that I very much need."
She added: "I have made a grave error and I consider myself to have taken a wrong turn in the course of my life." The family said they would help the couple "overcome their addiction".
At the time, the Metropolitan Police Commissioner Sir Ian Blair said he found the outcome "extremely surprising", adding: "It reminds me of the 19th-century legal comment often attributed to Sir James Mathew: 'In England justice is open to all – just like the Ritz'."
The incident was seen as particularly shocking among their high society friends, as Ms Rausing had long campaigned against drug abuse and was a patron for Mentor, a drug prevention charity set up by Queen Silvia of Sweden.
Ms Rausing's friends included Prince Charles, who refused to sack her as a trustee from one of his foundations following the scandal at the embassy. The Prince described her as a "very special philanthropist" following her support for a series of drug charities.
Mr Rausing, the youngest of Hans Rausing Snr's three children and known as Hans K to his friends, was re-arrested in connection with his wife's death yesterday.
His father lives on a 900-acre estate in East Sussex after moving from Sweden in 1982 to avoid the country's high taxes – while his sisters have developed reputations for philanthropy and academic pursuits.
Mr Rausing Jnr fell into drugs after dropping out and hitting the hippie trail in India in his 20s. One friend said in 2008: "Where else was he to go? He had no discernible interests anyone knew of, and his dad had made more than God. It's not as if he was going to make any more."
Ms Rausing is the daughter of Tom Kemeny, a multi-millionaire former Pepsi executive who owns an island off South Carolina.