Anna Florence Reed, 22, was discovered lifeless on the bathroom floor hours after fellow guests are reported to have reported a violent row in her room.
She had apparently been asphyxiated.
Her boyfriend, said by staff to be “in an agitated state”, has been arrested.
Worried guests at the £200-a-night four-star Hotel La Palma au Lac, Locarno, reportedly alerted staff after shouting and screaming was heard on Monday evening and the night porter was sent to the room.
But at 6.30am the next morning her boyfriend left their penthouse room and took a lift to the lobby.
A hotel source said: “Early on Tuesday morning he appeared in the reception. He was agitated and said his girlfriend had a problem with her health, that she was ill.
“The receptionist could tell by his tone that it was serious so called an ambulance. The medics went straight up to the room. She was on the floor of the bathroom.
“They tried to resuscitate her but there was no response. She was already dead. It was the ambulance crew who alerted the police.”
A post-mortem examination was said to have confirmed she died from suffocation or asphyxiation and had small fractures and cuts on her body, according to local media reports.
Swiss police said in a statement: “A 29-year-old man has been arrested and a file has been sent to the local prosecutor with an allegation of pre-intentional homicide.”
The charge relates to a murder that is not premeditated.
Police sources say the lover, who is understood to live in Zurich, had claimed her death was an accident during “an erotic tryst”.
Anna, born in Harrogate, North Yorks, is related to the late horse race stable owner and breeder Guy Reed who also formed Reed Boardall haulage giants.
She was educated at the town’s renowned private school Ashville College, which charges up to £10,000 a term.
Anna, who wrote on social media under the name Berlin Baby, had posted several photographs of herself in exotic locations in recent weeks.
It is believed she was enjoying a round-the-world trip as part of a 21st birthday present from her father, Clive, 62.
A number of pictures taken in recent weeks showed her cosying up to a muscular man.
Yesterday a former friend revealed how Anna had been badly affected by the death of her mother Mary at 49 who fell down stone stairs in 2014.
The friend said: “She used to attend Ashville but she moved to Germany after her mother died. By all accounts she went off the rails and became something of a wild child.”
Last night her father, who lives in North Yorkshire, and sister Millie, 24, flew to Switzerland.
Alongside the stud farm, Mr Reed also runs health and social care support firm Northern Life Care with his brother, John.
Accounts show the company has a turnover of £25million and total assets of £12million.
An employee of Mr Reed said: “Clive is utterly devastated and no one can believe what has happened. It is terrible, just absolutely shocking.
“This is the second awful tragedy to hit the family. I didn’t know Anna but everyone said she was a very bright and beautiful young woman.”
A Foreign Office spokesman said: “Our consular staff are assisting the family of a British woman following her death in Switzerland and are in contact with the Swiss and UK police.”
‘He was agitated and said his girlfriend had a problem’