LONDON -- The heir to the Tetra Pak drinks-carton fortune has been arrested in connection with his wife's death, reports said Friday, but police have had to delay questioning him while he is treated for alcohol withdrawal.

The body of American-born Eva Rausing, 48, was found Monday in the couple's London home. Police have said the death is being treated as unexplained, but her husband, Hans Christian Hausing, 49, remains in police custody.

The Telegraph quoted Detective Inspector Sharon Marman as telling Westminster Coroner's Court on Friday: "We have not yet been in a position to interview Mr. Rausing. He has been arrested on suspicion of her murder and we await notification of when he would be fit to be interviewed by police." 

Although the detective used the word "murder," the Guardian reported that the official inquiry remains an investigation into an "unexplained death." One of the theories being examined, the newspaper said, was that Rausing died of a self-administered overdose.

Struggles with substance abuse
Eva Rausing, a mother of four, was one of the wealthiest women in Britain at the time of her death. Her husband's family is worth an estimated $6.7 billion, according to The Telegraph. The family was ranked as Britain's 12th richest in the 2011 Sunday Times Rich List.

Police found Eva Rausing's body in the couple's west London home after arresting Hans Christian Rausing for driving erratically. Reports suggest she had been dead for up to a week before her body was found.

Police struggle to shed light on US-born heiress' death

British tabloids have documented Eva and and Hans Christian Rausing's long struggles with substance abuse.

In 2008, Eva Rausing was arrested outside the U.S. Embassy in for reportedly trying to bring crack cocaine and heroin into building 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.

Before the embassy arrest, Eva Rausing's good looks and beautiful clothes — along with her husband and his friendly, bear-like countenance — had made the Rausings welcome participants on the London philanthropic scene. She was on several charity boards, focusing on those that helped fight drug addiction, but also serving on Prince Charles' Foundation for the Built Environment.

Evidence suggests that Eva Rausing's drug use intensified in the years since the embassy arrest. Recent photographs showed that Eva Rausing had become quite gaunt, and her once stocky husband also recently appeared thin and furtive, bearing only a slight resemblance to his former self.

Liz Brewer, a friend of Eva Rausing, told Britain's Sky News that Rausing's problem had been "pushed under the carpet" for too long.
"She was totally addicted, obviously, and was trying to get off it," Brewer said. 

The Associated Press contributed to this report.

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