Eva Rausing’s body may have lain undiscovered for up to four weeks, it was reported today.

The body of 48-year-old Mrs Rausing, who was married to billionaire Tetra Pak heir Hans Kristian Rausing, is thought to have been in a state of advanced decomposition that tallies closer to a discovery four weeks after death than the one week initially thought.

The Mail Online reported that Mr Rausing’s body was found only after police forced their way past her Filipino housemaid, as they searched for drugs. Mrs Rausing’s body was subsequently found in an upstairs bedroom.

Police initially attended the Rausing’s £70 million Georgian mansion after Mr Rausing was seen driving erratically in south London and was subsequently arrested on suspicion of possession of Class A drugs. Police then moved to search the couple’s home for drugs several hours later.

Mr Rausing, 49, is in a secure hospital receiving treatment for a mental breakdown and drugs withdrawal. He remains under arrest on suspicion of murdering Mrs Rausing, but cannot be interviewed by police until medical staff declare him fit.

Investigators are now studying CCTV footage from outside the couple’s six story Cadogan Place mansion to try and establish Mrs Rausing’s final movements, as well as find out exactly who entered and left the building in the weeks before her body was found.

Be Kemeny, Mrs Rausing’s 47-year-old sister, said she had travelled to London from the United States in June and had not been able to find Eva, despite banging on her locked bedroom door.

Ms Kemeny said: “The housekeeper let me in and I went upstairs to her bedroom and I was knocking on the door and texting her and calling out to her and there was no reply…I think my sister was in there, passed away. I’d been worrying for weeks. I suspected something awful had happened.”

Advanced decomposition meant an initial autopsy on Mrs Rausing’s body failed to deliver a cause of death. A second autopsy may now take place this week on the instructions of Mr Rausing’s legal team.