Hans Kristian Rausing lived with his wife Eva’s body for four days

Tetra Pak billionaire Hans Kristian Rausing may have lived with his wife Eva’s dead body for up to four days before it was discovered by police.

Despite living in a vast $24 million Belgravia mansion, the couple – who had fought a long battle against addiction to hard drugs – had become increasingly reclusive, confining themselves to two squalid rooms.

Details of the extraordinary and tragic lifestyle of one of Britain’s richest couples emerged as Scotland Yard continued to investigate the “unexplained death” of 48-year-old Eva Rausing.

Investigators now believe Eva Rausing may have been dead for three or four days in an upstairs bedroom of the house before being discovered by police.

Officers are studying phone, text and email messages to see when she last used them and CCTV security footage to try to discover whether Hans Kristian Rausing spent time in the house during the period his wife was dead.

One friend who claimed to have recently visited the Cadogan Place address said the couple has been living virtually in two rooms which he described as a “drugs den”. Much of the sprawling house, he said, was “unused”.

The friend added: “It was total squalor. Really messy. You wouldn’t believe they were billionaires. It shows the effects of drugs.

“They couldn’t look after themselves or their house. They only used two rooms despite having dozens. It’s very sad indeed.”

The couple is said to have become “reclusive” in recent months and when he went out Hans Kristian Rausing chose often to use the vast property’s rear entrance.

Last night Hans Kristian Rausing was said to be in a secure “medical facility” receiving treatment. He is said not to have suffered any self-inflicted injuries but to be having treatment for a breakdown.

Recent pictures show Hans Kristian Rausing to be a shadow of his former self and it is understood that when officers tried to question him – initially about the possession of drugs and hours later about the discovery of his wife’s body – he struggled to speak coherently and failed to answer their questions.

Both Hans Kristian and Eva Rausing – friends of Prince Charles – have fought a long, painful battle against drug addiction and both were cautioned four years ago by Scotland Yard for drug offences.

They met while in a drug rehabilitation centre in the United States and friends say they struggled to beat their addictions.

Socialite Liz Brewer, a friend of Eva Rausing, said: “She was totally addicted and was trying to get off it.

“The last time I saw her was a couple of months ago. She had cut herself off from people for a while.

“Eva tried hard to turn things around and went to about every rehab around.

“I heard she may have been dead in the house for a while, but it was rare for him [Hans] to be out of the house for more than a few hours.”

Jules Hearn, a friend for 15 years, said Eva Rausing’s death was “inevitable”. She said her friend had resorted to blood transfusions after years of drug abuse, and relied on a pacemaker to regulate her heart.

After laying a rose outside the Rausings’ house yesterday, she said: “She was a troubled soul. Everyone thought this was going to happen one day. She tried to help herself again and again but it is an illness.”

Police are examining CCTV footage to track the couple’s movements as well as those of anyone entering or leaving the house.

Three members of staff have been questioned. Bank records were also being examined for signs of recent withdrawals or transactions.

A post-mortem examination failed to reveal how Eva Rausing died and toxicology and other tests are under way. There were no obvious injuries or wounds to the body and it is likely to be several days before full results are known.

Scotland Yard would not comment yesterday on whether any Class A drugs were found at the Cadogan Place house where Eva Rausing and her husband had lived for 13 years.

It emerged yesterday that Hans Kristian Rausing was stopped and arrested on Monday while driving erratically in Wandsworth, South London.

He was found to be in possession of Class A drugs and this led police to search the six-storey house where his wife’s body was found.

Neither Hans Kristian or Eva Rausing have fallen foul of the law since the incidents in 2008 when she was stopped trying to take drugs into the US Embassy and heroin and cocaine were subsequently found in their home.

Hans Kristian Rausing’s father, Dr. Hans Rausing, 86, and mother Marit are said to be monitoring the progress of the investigation and their son’s treatment from their 900-acre estate in East Sussex.

Eva Rausing’s devastated parents Tom Kemeny, an executive with Pepsi Cola, and his wife Nancy, who lived close to her in Cadogan Place, have put out a statement acknowledging how “she bravely fought her health issues for years”.