Kasia Gallanio was born to Polish parents in Los Angeles.
A Qatari prince's ex-wife was found dead at her home in the Spanish resort of Marbella, Independent reported on Wednesday. Kasia Gallanio, the third wife of billionaire Abdelaziz bin Khalifa Al Thani, was fighting a bitter legal battle with her former husband for the custody of her three daughters.
Independent said in its report that Ms Gallanio died after a suspected drug overdose on Sunday. She had been engaged in a bitter legal battle for 15 years over the custody of their children.
Ms Gallanio left her husband, the uncle of the Emir of Qatar, after allegations that her husband sexually abused one of her three daughters, The Daily Beast reported.
While she lived in Marbella, the three children remain with their father living in Paris. Al-Thani has always denied the allegations.
Ms Gallanio, 45, who was born in Los Angeles, married 73-year-old Al-Thani in 2004. Al-Thani had moved to Paris in 1992 after he was cast out of the royal family for allegedly trying to overthrown the Emir.
French media reported that Ms Gallanio was battling depression and addictions to drugs and alcohol while living alone in Spain. She had recently spent several months in hospital, with the French publication saying she was prone to suffering from nervous breakdowns.
A post-mortem will be done on Tuesday, the Beast further said in its report.
The police visited her palatial house after getting complaints from her children that she had not responded to their phone calls for several days.
The police have launched an investigation into the circumstances surrounding her death.