And the actor has warned that the revelation is going to be heart-breaking and said fans will get the answers sooner than they expect when the show returns this September.
"Jack's ultimate death, I think that question may get answered relatively quick. When I signed on for the pilot, I knew that Jack was deceased in the present day," Ventimiglia told Variety.
"So it wasn't a surprise when (creator) Dan Fogelman finally told me how it all happened. It's going to break some hearts wide open when it happens, but it's a pretty amazing, magical moment to see what Dan has planned."
Talking about how the character has the 'same heart as his father', he said, "I approach Jack very simply, because he's a simple-needs kind of guy. He loves his wife, he loves his kids, and will do anything for them.
"He's a good person, and inspires people around him to be good. I very much try to be a good man, too."