When Monaco’s richest woman was gunned down after visiting her son in a Nice hospital, the gangland-style murder stunned the Principality amid reports of a Mafia hit. 

But rather than a mob boss, it is her daughter’s lover who will go on trial in Aix-en-Provence on Monday, accused of ordering her 2014 killing to gain greater access to her fabulous wealth. 

Hélène Pastor, 77, was a hard-nosed businesswoman who owned a huge slice of some of the world’s most valuable real estate. Closely linked to Monaco’s royal family, she was known as the “deputy princess”.

She disapproved of her daughter Sylvia’s longtime live-in partner, Wojciech Janowski, 69, an elegant, charming and flamboyant Pole, and hired…