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MIAMI (CBSMiami) – A family is filled with mixed emotions on the day the U.S. and Iran reached a historic deal in securing a nuclear program.

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Robert Levinson, a Coral Springs resident, who is being held hostage in Iran disappeared in 2007 while working as a private investigator and consultant for the CIA.

Dan Levinson, one of Levinson’s sons, spoke out about how he feels on this historic day.

“The biggest feeling for me today is that I’m a little disappointed,” said Dan Levinson. “It’s been an absolute nightmare.  This is longer than 8 years now and every day is just a nightmare, thinking about how much he’s suffering and how all he wants to do is get home to everyone he knows and loves.”

In 2010, the family received video and pictures of Levinson detained but they have not heard a word since.

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Levinson is one of four American hostages being held in Iran.

Secretary of State John Kerry vowed to continue to fight for their release.

“And certainly, we continue to call on Iran to immediately release the detained U.S. citizens. These Americans have remained in our thoughts throughout this negotiation. And we will continue to work for their safe and their swift return and we urge Iran to bring our missing Americans home as well,” said Kerry.

Dan Levinson said he and his family are hoping for the best, that the improved relations between the two nations will one day pave the way for his father’s safe return home.

Meantime, he’s appealing to those who can make it happen.

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“I actually just got off the phone with the State Department before this interview and they said they’re going to continue to press this case and that they’re going to be talking to the Iranian government about my father and continue to do as they had been doing,” said Dan Levinson.