LONDON — In what has been depicted in part as a parable of high-society travails and in part as a police-beat mystery with shades of Raymond Chandler, investigators awaited the outcome Wednesday of further tests to discover what killed U.S.-born Eva Rausing, one of Britain’s richest women, after her body was discovered at her upmarket home and her husband arrested.

The tale — entwining ultrarich philanthropists, a history of drug abuse and many unanswered questions — has seized British headlines since Monday.

That was when Hans Kristian Rausing, 49, an heir to Tetra Pak, a multibillion-dollar global food-packaging empire born of a milk carton, was arrested on suspicion of possessing illegal drugs. Hans Rausing had apparently been driving erratically in south London.

But when police went on to search the couple’s luxurious, five-story mansion in London, they discovered the body of Eva Rausing, 48. It was not clear how long she had been dead.

The Daily Mail tabloid and other British newspapers said Wednesday that the body may have been undiscovered in a bedroom for several days. Newspapers published what they said were recent photographs of the couple looking “drawn and disheveled.” An initial postmortem examination Tuesday failed to establish a formal cause for the death.

Police officers were photographed Wednesday lugging boxes of forensic equipment through the entrance to the Rausings’ home, while another officer stood guard.

“Officers from the Homicide and Serious Crime command are investigating, and the death continues to be treated at this time as unexplained,” a police statement said.

Hans and Eva Rausing met while they were in rehab 25 years ago, and came to support many causes, including some associated with addiction.

While police have declined to formally identify the man they have arrested following the discovery of Eva Rausing’s death, her husband has been widely identified in press reports, and police have given details of the case in response to questions about him.

He was initially held in a south London police station but has since been moved to a medical facility.

A statement from Eva Rausing’s family said her parents, Tom and Nancy Kemeny, “along with all of their family are deeply saddened by the death of their beloved daughter, Eva Louise Rausing.”