U.K. billionaire Eva Rausing's husband Hans Kristian Rausing arrested on suspicion of murder

Updated at 10:11 a.m. ET

(AP) LONDON - The husband of Eva Rausing, one of Britain's richest women, has been arrested on suspicion of murder in the death of his wife, even though no cause of death has been established, police said Friday.

The body of 48-year-old Eva was found Monday at the couple's London home. The Metropolitan Police say detectives are treating the death as "unexplained," and Hans Kristian Rausing has not been charged.

However, Detective Inspector Sharon Marman told a preliminary inquest hearing Friday that "Mr. Rausing ... has been arrested on suspicion of her murder."

He is receiving medical treatment and has not yet been questioned by detectives.

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Marman said a post-mortem examination failed to establish the cause of Eva Rausing's death and police were awaiting the results of further tests. It was unclear how long that might take.

Hans Kristian Rausing is an heir to the Tetra Pak drinks-carton fortune. He and his U.S.-born wife lived in a luxury townhouse in a leafy London square, donated millions to addiction charities and had a long history of drug use.

Hans Rausing's Swedish father helped transform Tetra Pak into a hugely successful manufacturer. The fortune of the senior Rausing and his family is estimated at 4.3 billion pounds ($6.7 billion) by the Sunday Times Rich List.

They were arrested in 2008 after Eva Rausing was caught trying to smuggle crack cocaine and heroin into the U.S. Embassy in London in her handbag. Police later found small amounts of cocaine, crack and heroin in a search of the couple's house. They were charged with drug possession but prosecutors later agreed to drop the charges in exchange for formal police warnings.

At the time, the Rausing family issued a statement saying relatives were "deeply saddened" by the couple's drug problems and hoped they could overcome their addictions.

One of the charities that Eva Rausing supported — Action on Addiction — was among the first to express sadness over her death and praise her "wonderfully generous" support over the years.

She also was listed as a long-time supporter of The Prince's Foundation, part of a group of nonprofit charities that have Prince Charles as their patron. His office said earlier this week the prince was told of Rausing's death but did not offer further comment.