02/08/2012 at 05:00 PM EST
Oscar-winner Marisa Tomei
recently traveled to Italy to investigate a murder mystery – and no, that's not the plot of her latest on-screen project.
Tomei, 47, made the journey to look into the death of her great-grandfather, as part of NBC's Who Do You Think You Are?
, which gives celebrities a chance to delve into their heritage. The Ides of March star
examined records at an Italian church in order to piece together her family history.
Growing up, family legend was that the actress's great-grandfather was a womanizer and a gambler whose philandering ways led to him being fatally shot in a bar, according to the NBC show. But documents that Tomei uncovered in Italy cited his cause of death as "illness."
"The mystery still remains between the story of this murder and then this supposed illness," Tomei
says in a video clip. "That still all seems suspect. So I'm just looking for any other kind of records that could connect those dots."