(CNN) -- David Goldman says he can't understand why he can't have custody of his son following his ex-wife's death in Brazil. The U.S. government agrees.





David Goldman is fighting for custody of his son after Bruna Bianchi Goldman died during another childbirth.





Goldman told CNN's Larry King he had no idea when he dropped off his wife and 4-year-old son at Newark International Airport in 2004 for a two-week vacation to Rio de Janeiro, Brazil, that he was about to become embroiled in an international custody battle.





Shortly after Bruna Bianchi Goldman arrived in her homeland she called to say she wanted a divorce, which she obtained in Brazil, and would stay there with their son, Sean.





The running custody battle has taken many twists and turns and has gained the attention of the Department of State and Secretary of State Hillary Clinton.





"A child belongs with his family, and there is no reason why David Goldman should not get his child back," Clinton said in a recent interview on NBC's Today show. "And we're hoping that that will be resolved very soon. Obviously, if not, we will continue to raise it with the Brazilian government."





For nearly five years, Goldman has fought to regain custody of his son. It's a case that has been complicated by Bianchi Goldman remarrying, getting pregnant and dying during childbirth last summer. Sean Goldman is said to be living with his stepfather, who has been granted provisional guardianship.





"I went down ... to bring my son home," Goldman said on CNN's Larry King Live Wednesday, figuring his ex-wife's death had made the custody issue a moot point, and "we find out that this man doesn't file custody, but he files to remove my name from a Brazilian birth certificate that they had issued for my son, who was born in Red Bank, New Jersey."





Goldman continues to press his case through the U.S. government.





"The Department of State is working diligently to ensure that David and Sean Goldman are accorded their rights under the Hague Convention of 1980 on the civil right aspect of International Child Abduction," the agency said in a statement. "We'll continue to insist that the Brazilian government fulfill its obligations under the treaty and international law."





The convention, to which Brazil is a signatory, "is a multilateral treaty, which seeks to protect children from the harmful effects of abduction and retention across international boundaries by providing a procedure to bring about their prompt return," according to the Hague Convention Web site.





Brazilian courts have refused to return Sean Goldman to the United States for any custody hearings that New Jersey courts have ordered and the Brazilian government has not intervened. As a result, the case remains a stalemate.





"I would tell him that he's been very brave, as he has fought to have his son returned to him," Clinton said in the NBC interview. "His son is the most precious person in the world to him and he has gone not just the extra mile, but mile after mile, back and forth, trying to make it clear that his son Sean deserves to be returned to him."





But on Larry King Live, Helvecio Ribeiro, a Bianchi family spokesman, questioned Goldman's fitness as a parent.





"I don't question the biological right," he said. "The fact of the matter is that in order to be a parent, you have to be more than just a DNA donor, Mr. King. Fatherhood is not about making home movies and taking pictures, it's about sacrifice. It's about providing support to your child. It's about being there even when you're not there.





"And Mr. Goldman, while Bruna was still alive, failed to do so," Ribeiro said.





Goldman visited his son for the first time in more than four years last month -- a bittersweet experience that was heartbreaking when it was time to return to the United States.





"He asked me why I haven't come to see
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