Monaco’s royal family has been shaken by the unexplained death of Prince Albert’s cousin, whose body was found in a public garden.
The body of Antoine de Massy was discovered on Sunday along Boulevard du Larvotto, a major thoroughfare in the principality.
According to AFP, the 29-year-old was last seen staggering away from a nightclub in the early hours of Sunday morning.
Monaco Matin reported that he was declared missing after failing to attend a family lunch. His body was found soon afterwards.
Police arrested a Ukrainian national on Monday after he was captured on CCTV near the location where Mr de Massy was found.
Monaco’s Public Prosecutor’s Office said the man’s involvement had not been established. Investigators are examining every possibility, including an accident, as they work to determine the cause of death.
Mr de Massy was the grandson of Prince Albert’s aunt, Princess Antoinette, making him Albert’s first cousin once removed.
The Prince’s Palace announced his 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, grandson of Princess Antoinette, the elder sister of Prince Rainier III.
‘A passionate tennis player, he belonged to a family whose history was closely connected with the sport in the Principality.
Antoine de Massy’s body was found on Sunday in a public garden in Monaco
He was Prince Albert II of Monaco’s first cousin once removed
Prince Albert of Monaco and Princess Charlene said they were ‘saddened’ by Antoine de Massy’s death
‘Their Highnesses share the grief of his family and loved ones and extend their sincere condolences at this painful time.’
Mr de Massy played professional tennis and moved with his family to Florida at a young age to train at the prestigious Nick Bollettieri Tennis Academy. He had hoped to compete in the Olympics.
Speaking to Vogue Italia in 2012, he said his ambition was to ‘become number one in the world’, adding that reaching ‘even the top 20 wouldn’t be bad!’
More recently, he co-founded Instant Tech, a technology company designed to connect local businesses, merchants and customers for immediate reservations and payments.
Despite his royal ties, he reportedly kept away from the spotlight and largely avoided Monte Carlo’s social scene, according to Bild.
One of his final public appearances came at Monaco’s traditional Te Deum Mass for National Day in November 2025.
His father, Baron Christian de Massy, has often been described as the family’s black sheep. He was expelled from school and sent to Argentina during his youth after causing repeated trouble. Local media dubbed him a playboy, and all four of his marriages ended in divorce. He is seldom seen at social occasions alongside Monaco’s royal family.
The death follows a bombing attack in Monaco this summer that injured Ukrainian business tycoon Vadym Yermolaiev, who has links to Russia.
His body was found in a park along the Boulevard du Larvott in Monaco (street view)
Antoine de Massy (top right) with members of Monaco’s royal family
A woman and a child who were with him were also injured.
Days after the attack, a woman suspected of trying to kill the businessman was found dead in Ukraine with gunshot wounds to her head, according to Ukraine’s Security Service.
A Ukrainian military intelligence officer confessed to killing the bombing suspect, Anastasiia Berezovska, with the help of a former law enforcement officer, the security service, known as the SBU.
The military intelligence officer said he acted on his own and without the knowledge of his superiors, the SBU said.
Both men were detained on suspicion of murdering Berezovska, a Ukrainian national whose last known residence was in Germany, according to authorities.
They also ‘may have been involved in planning’ last week’s bombing, Monaco prosecutor Stéphane Thibault said at the time.
The attack shocked Monaco, a coastal playground for the rich and famous known for its tax-friendly incentives, royal family and Formula 1 Grand Prix.
Ukraine is believed to have carried out attacks and targeted killings of Russian figures in the course of the war; however, those attacks have largely been confined to Ukrainian or Russian territory.
It comes after a bombing attack rocked Monaco this summer, injuring Ukrainian business tycoon Vadym Yermolaiev
One possibility is that the bombing in Monaco and Berezovska’s killing are connected to the Yermolaiev family’s business dealings, said political analyst Volodymyr Fesenko.
Fesenko noted that at the end of April, Yermolaiev’s son, Artur, settled charges brought against him in Estonia related to an alleged phone scam that took in more than 100 million euros from citizens in multiple European countries between 2019 and 2022, according to local media reports.
As part of the deal, the younger Yermolaiev paid an 8.5 million euro fine.
Monaco’s head of state, Prince Albert II, described the bombing as ‘an odious act.’
Yermolaiev built his fortune through the Alef Group, a diversified business that includes commercial real estate, manufacturing and agriculture.
Sanctioned by Ukraine in 2023 for his ties to Russia, Yermolaiev has said he renounced his Ukrainian citizenship nearly a decade ago.