Police are investigating the grim possibility that Hans Rausling lived with the body of his dead wife, Eva, for a week at their £70m London home.
The state of the body was such that pathologists have been unable to find a cause of death, making this theory a distinct possibility, reported The Daily Telegraph.
A Met Police spokesperson confirmed it was one line of enquiry they were chasing up, telling The Huffington Post UK: "The question of how long the body had been in situ is part of the ongoing investigation. It's very early days."
Meanwhile, recent pictures have emerged of Hans and Eva Rausling walking close to their home just months before the 48-year-old heiress was found dead.
Taken in May, the images show Hans, the heir to a £5.4bn fortune, looking dishevelled in a baseball cap. His wife was discovered dead on Tuesday in the couple's dwelling on Cadogan Place, one of the most exclusive streets in London.
Hans and Eva Rausing in Chelsea in May
Hans Rausing, whose family owns the Tetra Pak drinks carton empire, is being held by police.
He was taken into custody at a south London police station but has since been moved to a "medical facility" where he is receiving medical attention, police said.
Scotland Yard would not confirm the name of the suspect, but said a 49-year-old man was arrested in south London on Monday morning on suspicion of possession of drugs.
Hans Kristian Rausing and his wife Eva in 2003
Later that afternoon, officers conducted a search of the property where they discovered Mrs Rausing's body.
The man was then further arrested in connection with the mother-of-four's death. His bail has been suspended while he receives ongoing medical treatment, the force said, while security staff were called in to retrieve CCTV footage from the couple's home.
Police are treating the death of Mrs Rausing as "unexplained" and a post mortem held on Tuesday failed to establish a formal cause of death. Investigators said they are awaiting the results of further tests in the hope they will shed some light on the death riddle. Officers refused to comment on speculation that the Mr Rausing had suffered some form of mental breakdown.
A Met Police spokesman said: "Officers from the Homicide and Serious Crime Command are investigating, and the death continues to be treated at this time as unexplained."
Grieving relatives of the married couple, whose past drug problems have been widely reported, last night revealed their sorrow over the death.
A statement from the family of Mrs Rausing, whose maiden name was Kemeny, said: "Tom and Nancy Kemeny along with all of their family are deeply saddened by the death of their beloved daughter, Eva Louise Rausing.
"Eva was a devoted wife for 20 years and mother of four much-loved and wonderful children.
"During her short lifetime she made a huge philanthropic impact, supporting a large number of charitable causes, not only financially, but using her own personal experiences.
"She bravely fought her health issues for many years. The family is devastated at her death and asks to be given privacy at this difficult time."
In a statement issued from his Sussex estate, Mr Rausing's famously reclusive father, 86, also called Hans, said the family was "deeply shocked and saddened to hear of the tragic death of their daughter-in-law" and also asked for their privacy to be respected.
Mr Rausing, then 45, was charged with drugs offences after police found crack cocaine, cocaine and heroin during a search of his home.
After lengthy discussions between his legal team and prosecutors, he accepted a conditional police caution instead.
Neither Mr Rausing nor his wife, who also faced drugs charges, was present at City of Westminster Magistrates' Court that August to hear that the prosecution had ended.
Police outside the couple's home in Chelsea, London
The couple had been arrested in April of that year after Mrs Rausing was caught with drugs as she tried to enter the US Embassy in London.
Court documents revealed Mrs Rausing, then 44, was carrying about 10g of crack cocaine, 2.5g of heroin and 2.35g of diethylpropion, a banned stimulant and appetite suppressant.
A further drugs stash, 220mg of diazepam, used to treat anxiety, was also found in her Renault Clio car.
The couple's £5m Georgian five-storey town house in Cadogan Place was subsequently searched.
Officers found 0.2oz (5.63g) of crack cocaine, 0.1oz (2.9g) of heroin and almost 1.8oz (52g) of cocaine.
The conditional cautions, administered by a senior local officer, meant the couple admitted possessing the drugs.
Mr Rausing's parents and siblings said then they were supporting the couple as they fought to overcome drug addiction.
Comments have been closed for legal reasons.