Antoine de Massy, a cousin of Prince Albert of Monaco, is believed to have died after falling 40ft in a public garden on Sunday.
Questions are also being raised about a possible connection to a cryptocurrency scandal, while a Ukrainian national has been arrested over the death.
De Massy’s body was found behind Monaco’s New National Museum, near Boulevard du Larvotto.
Reports say he was last seen staggering away from a nightclub during the early hours of Sunday.
The 29-year-old was reported missing after failing to appear for a family lunch, according to local newspaper Monaco Matin. His body was discovered soon afterwards.
Police arrested a Ukrainian national on Monday after CCTV showed him near the location where De Massy’s body was found.
Investigators determined that the 42-year-old had been in contact with De Massy. However, he declined to answer questions when he appeared before a judge on Wednesday.
The suspect remains in pre-trial detention and faces allegations of involuntary manslaughter and failing to assist a person in danger.
Autopsy findings indicate that the royal most likely died after falling approximately 40ft from a building in the area.
Meanwhile, rumours have emerged that the 29-year-old may have had ties to a cryptocurrency controversy.
Antoine de Massy’s body was found on Sunday in a public garden in Monaco (Source: Instagram/antoinedemassy)
Prince Albert of Monaco and Princess Charlene said they were ‘saddened’ to hear of Antoine de Massy’s death
Antoine de Massy (top right) pictured with members of Monaco’s royal family
An investigation by BILD reported that De Massy was active in Monaco’s blockchain sector. Blockchain is a shared digital database that records information across a network of computers.
He founded Instant Tech in 2021, a company designed to connect local businesses, merchants and customers for instant bookings and payments. He also co-founded the Association Cryptographique de Monte-Carlo.
An unnamed source told BILD that De Massy was rumoured to have links to the controversial cryptocurrency exchange Zondacrypto.
The Polish-founded company is being investigated by authorities after collapsing in 2026, leaving thousands of customers unable to access their funds.
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The reported losses are estimated at no less than 79.5million euros, while Polish authorities are investigating suspected fraud and money laundering.
No connection between De Massy and Zondacrypto has been proven. However, an insider close to the Grimaldi family told BILD that he was a prominent figure in Monaco’s technology community.
‘It shows that Prince Albert II had placed his trust in the ambitious young entrepreneur. Without the prince’s approval, Antoine would not have been able to take on these positions in the tech scene,’ the source said.
Meanwhile, Monaco has been under increased scrutiny by the Financial Action Task Force since 2024, and is on the international grey list of high-risk countries for money laundering.
The Financial Action Task Force has pointed to weaknesses in the fight against money laundering in the principality.
These include insufficient controls, shortcomings in investigations, and deficiencies in tracing criminal assets.
His body was found in a park along the Boulevard du Larvotto in Monaco
According to an inside source who spoke to BILD, De Massy is rumoured to have been connected to the controversial cryptocurrency exchange, Zondacrypto (Source: Instagram/antoinedemassy)
The prince’s palace announced De Massy’s death in a statement on Monday: ‘Their Serene Highnesses Prince Albert II and Princess Charlène were saddened to learn of the death of Antoine de Massy, the grandson of Princess Antoinette, the elder sister of Prince Rainier III.
‘A keen tennis player, he was part of a family history closely linked to the sport in the principality.
‘Their Highnesses share in the grief of his family and loved ones and offer them their sincere condolences at this painful time.’
De Massy played tennis professionally and moved to Florida with his family when he was younger to train at the prestigious Nick Bollettieri Tennis Academy, with hopes of making it to the Olympics.
In a 2012 interview with Vogue Italia, he said his dream was to ‘become number one in the world,’ adding, ‘even in the top 20 wouldn’t be bad!’
Despite his royal connections, he preferred to stay out of the spotlight in Monte Carlo’s social scene, according to BILD.
One of his last public appearances was at the traditional Te Deum Mass for Monaco’s National Day in November 2025.
His father, Baron Christian de Massy, is often referred to as the black sheep of the family, having been kicked out of school and banished to Argentina for causing too much trouble in his youth.
Dubbed a playboy by local media, all four of his marriages ended in divorce. He is rarely ever seen at social events with the Monaco royal family.