( CNN ) -- The son of one of the world 's wealthiest men is under arrest in London after the body of his American-born wife was found in their home this week , her death unexplained . Police stumbled into the mystery Monday , when they arrested Hans Kristian Rausing on drug charges . A search of his home in one of London 's most expensive neighborhoods turned up the body of his wife , Eva , spurring police to arrest him again in connection with the death . Eva Rausing had struggled with drug addiction for years , an acquaintance said . `` This has been an existing problem for a long time , '' said Liz Brewer , who knew Rausing through charity and social circles . `` I think the whole thing is a complete tragedy . '' The case puts the multimillionaire couple squarely back in the headlines four years after they were arrested on charges of possessing cocaine and heroin , according to media reports at the time . Eva Rausing had tried to smuggle a small amount of crack cocaine and heroin into the U.S. Embassy in London , reports said . She and her husband were arrested when police found more drugs at their house . The pair , however , avoided prosecution . Since then , they have kept a low profile , Forbes magazine said in its annual rich list report this year . `` It 's very clear to us Eva had her own problems with drugs and drugs misuse , '' the head of an anti-drug organization told CNN Wednesday . `` She knew prevention was important . She knew how hard it was to get off drugs once you are on drugs , '' said Paul Tuohy , chief executive of Mentor . Eva Rausing had donated hundreds of thousands of dollars to the charity in the years before her death , Mentor said . Her husband is the son of Hans Rausing , who is worth an estimated $ 10 billion , thanks to the family 's connection to Swedish packaging giant Tetra Laval . Hans Kristian Rausing is now receiving medical treatment , police said Wednesday . An autopsy Tuesday failed to determine the cause of Eva Rausing 's death , police said . Police refused to name Rausing as the man who was arrested , but a source familiar with the investigation said the man in custody lived at the address where the body was found . The source asked not to be named discussing an ongoing investigation . Eva Rausing gave more than 500,000 pounds ( $ 778,000 ) to Mentor , said the charity , which runs programs `` to protect children from alcohol and drugs . '' J & J heiress , found dead , had high-profile life . Posts on a MySpace page dating back to 2007 that appears to belong to Rausing , but whose authenticity could not be verified , give a picture of her ups and downs . She writes that she went to college in California . `` I had a good time there -- too good , as I dropped out and did not go back to university until the grand old age of 24 . Which leaves some troubled years in between ... The beginning was fun , the ending not so fun , '' she writes . `` I was lucky to have a loving supportive family who stood by me , though I did n't always see it that way at the time . So , I cleaned up my act , became a good girl , if maybe a little boring , got a degree in economics , and then got married ! '' She says she is a good mother to the couple 's four children but , in an apparent reference to her drug abuse issues , she writes of relapsing several years earlier . `` I fell back into the same hole as before and have been there for nearly 7 years . I once read that I would have 7 bad years ( I do n't normally believe in hocus pocus horoscopes ) but so far it has been right , and I 'm hoping for 7 good years starting 2007 . `` I 'm still married , amazingly , to a very kind , patient and loyal husband . I 'm very lucky that he has stuck with me -- many would have not . '' Hans Kristian Rausing 's billionaire father was bought out of the Tetra Laval business founded by his own father . Tetra Pak declined to comment on Eva Rausing 's death or her husband 's arrest because their branch of the family `` divested its interests in Tetra Pak , and the Tetra Laval Group , in 1995 . '' CNN 's Dominique van Heerden , Susannah Palk and Atika Shubert contributed to this report .
NEW : A MySpace page apparently belonging to Rausing tells of her struggle with drugs . Eva Rausing had struggled with drug addiction for years , an acquaintance says . Score: 7 Rausing 's father is worth an estimated $ 10 billion .