(CBS News) NEW PROVIDENCE, N.J. -- Mari DiNardo counts the days since her husband passed away. Marc DiNardo was a 37-year-old father of three. The Jersey City detective was gunned down during a shootout captured on security cameras as his SWAT team moved in to make an arrest.
"It was two nights before they finally took him to surgery to harvest his organs," Mary DiNardo says. "And I listened to that heartbeat. So I'm hoping to be able to hear that heartbeat again."
She is about to meet the man who is living because her husband died.
"It's a miracle, and I just can't wait to meet him," she says. "Because Marc's still living. You know, a piece of him is living inside this man."
The heart now beats in Don Zolkiwsky's chest.
"You can't stop thinking about him," Zolkiwsky says when asked what it's like to have another man's heart in his body.
"I've had dreams consistently about the episode with the shootout," he says. "The noises, and I could almost sense what it must have been like to be in a room with a gun battle going on. That had to be horrific."
The 70-year-old knows what it's like to be in a gun battle. He earned a Purple Heart in Vietnam. A virus destroyed his heart before he received DiNardo's.
"He is like a buddy through the service," he says. "It's a bond, it's a friendship that I can't describe how the feeling is, but it's an intense one."
Four years ago, Zolkiwsky tried to put his feelings into words in a letter to Mary DiNardo.
"I can't explain it, but there is a deep sense of comfort and connection with the donor whom I've never met," he wrote. "Saying 'thank you' in person will lift some of the guilt that I carry as the survivor."
They finally met this week. A fallen hero's heart is now serving a war hero.
"You know, it may be in somebody else's body, but that was the heart that fell in love with me," Mary DiNardo says.
It is a hear that continues to beat -- for two families, forever.