The girlfriend's family accuses Carlo Alberto Ventre of kidnapping the child he and the woman had together, then killing Toni Dykstra after she traveled to Rome to get their daughter back.
Dykstra's twin, Teri Martinez, tearfully told 48 Hours correspondent Bill Lagatutta, "I miss her laughter. She was really funny. We would laugh about everything. And there's so many things I want to tell her."
Dykstra's mysterious death in Italy came in Ventre's apartment. He says the death was an accident, and that he loved Dykstra.
"I'm very sorry for what happened," he says. "The tragedy should have never happened but, unfortunately, it happened."
Their relationship began to fall apart, Lagatutta says, when their daughter was born.
Dykstra's father, Milt, and her stepmother, Betty, say Ventre had become obsessed with the child.
"He started his abuse the day the child was born," Betty says. "He would not allow Toni to have her. And he used threats. He physically hit Toni. He physically beat Toni."
In 1998, after the couple split, Ventre took their daughter with him to Italy, without Toni's permission, Lagatutta says. She argued to an Italian court that her daughter should be returned to her. She won the case.
But the day before she was to bring her daughter home, Lagatutta says, Toni Dykstra went to Ventre's apartment outside of Rome, where she died.
Her relatives think they know how.
"I think Toni was sitting there," Milt says, "and he went out and got this hatchet and walked up behind her and smashed her head. That's what I believe."
Ventre insists it was an accident, and that Toni fell and hit her head.
The Italian courts sided with Ventre and let him go, leaving the Dykstras furious. They wanted Ventre charged with murder.
"I hope that there really is a trial," says Martinez. "And I hope that all the facts come out. Not just his side of the story."
The Dykstras were given custody of the child, and that made Ventre furious.
He returned to the United States, where he was arrested for, then convicted of, kidnapping.
Now, six years later, through the efforts of the Dykstras, he has been deported to Italy, where the authorities are reconsidering murder charges.
In the interim, a custody battle fought in Los Angeles resulted in a court awarding custody of the daughter to Ventre's brother and sister-in-law, who live in Las Vegas.