Roman Sionis was a powerful criminal in Gotham City, also known as the Black Mask, and desired to consolidate his power. As the Bertinelli Crime Family were his biggest rivals in Gotham City, he desired their deaths.
Stefano Galante and other agents of Sionis rounded up the members of the Bertinelli crime family in the Bertinelli mansion, including Franco Bertinelli, Joe Bertinelli, Maria Bertinelli, Pino Bertinelli and Helena Bertinelli. Among one of the Sionis shooters was the criminal Victor Zsasz. They shot and killed the entire Bertinelli family, with the exception of young Helena. Though she was forced to witness her family's death, she was spared and spirited away to Italy by one of the gangsters to be raised by his father and brother.
While the massacre had the desired effect of consolidating Black Mask's power, it would, in the long term, be the undoing of him and his organization. While in Italy, Helena Bertinelli underwent intensive training, determined to get revenge for her family's slaughter. She re-emerged over 15 years later, going by the name of "Huntress" and wielding a crossbow pistol. She sought out and killed each of those who had slain her family, before finally teaming up with Harley Quinn, Cassandra Cain, Renee Montoya and Dinah Lance to take Sionis down.