Police make arrest after royal cousin found dead in park

Prince Albert of Monaco's cousin Antoine de Massy, whose mother was the sister of the late Prince Rainer, was found dead in mysterious circumstances in a park in the Larvotto district on Sunday.

Law enforcers detained a man, reported to be Ukrainian by local media, and held him for questioning day after shocking news of royal relative's death.

Monaco prosecutor Stéphane Thibault clarified to the Monaco Matin newspaper that the man is "at this stage merely a suspect/witness to events whose legal qualification remains to be determined, with the theory of an accident not being ruled out".

As per reports, Antoine's family rushed to police after he didn't show up at a family lunch on Sunday.

Some local outets report he was spotted with the man emerging from a nightclub in the early hours of the morning. A post-mortem examination into the cause of death is ongoing.

Antoine was the son of Christian de Massy, a sportsman, and Cécile Gelabale, Prince Rainer's sister.  This makes Albert, who inherited the throne from his late brother in 2005, Antoine's first cousin once removed.

After studying international relations and affairs at Florida International University in Miami, Antoine developed a tech start-up app. He was known as a keen tennis player and moved to Florida with his father to pursue the sport.

Antoine once said Novak Djokovic was his tennis hero "because he likes to joke on the field".

He said he hoped to one day become "world number one" in tennis, or "even making it into the top 20 wouldn't be bad".

Prince Albert and Princess Charlene 'saddened' after royal relative's death aged just 29, stating: "Their Serene Highnesses Prince Albert II and Princess Charlène were saddened to learn of the death of Antoine de Massy, aged 29, 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."