Alan Gross' wife: He won't last a year

• It's been five years since Cuban authorities arrested Alan Gross


• The former State Department subcontractor is serving a 15-year prison sentence


• "After five years of literally wasting away, Alan is done," his wife says


• The State Department renews its call for Cuban authorities to release Gross

(CNN) -- Judy Gross says she doesn't know how much longer her husband can make it. But she's scared it won't be long.

"Alan is resolved that he will not endure another year imprisoned in Cuba, and I am afraid that we are at the end," she said in a statement released Wednesday.

Her comments come on the five-year anniversary of the day when Cuban authorities arrested her husband, Alan Gross, who'd been working as a subcontractor the U.S. Agency for International Development.

Alan Gross, 65, is serving a 15-year sentence for bringing satellite communications equipment to Cuba as part of his work as a State Department subcontractor. He was convicted in March 2011.

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"After five years of literally wasting away, Alan is done," Judy Gross said. "It is time for President Obama to bring Alan back to the United States now; otherwise it will be too late."

The Cuban government has called for a prisoner swap: Gross for three imprisoned Cuban intelligence agents serving lengthy federal prison sentences in the United States.

But the U.S. State Department has nixed that idea, saying Gross was an aid worker merely trying to help Cuba's small Jewish community get online despite Cuban government restrictions on Internet access.

Frustrated by the diplomatic impasse, Gross has threatened to kill himself if he isn't freed soon.

In July, he said goodbye to his wife and daughter and has refused to see them again while he's imprisoned.

He's also refused to meet with U.S. diplomats in Havana in protest over the slow progress to free him.

On Wednesday, his family warned that his health is deteriorating. He's lost more than 100 pounds, he can barely walk because of chronic pain and he has lost five teeth and much of the sight in his right eye, the family's statement said.

The State Department renewed calls for his release on Tuesday, decrying his "unjustified imprisonment in difficult conditions in Cuba."

"It is gravely disappointing, especially in light of its professed goal of providing Cubans with Internet access, that the Cuban government has not allowed Mr. Gross to return to his family, where he belongs," the State Department said. "We reiterate our call on the Cuban government, echoing foreign leaders and even Cuba's allies, to release Alan Gross immediately."

Last month, U.S. Sens. Jeff Flake and Tom Udall traveled to Cuba to push for the former State Department contractor's release, calling his imprisonment an impediment to improving U.S. relations with the island nation.

Gross was arrested in 2009, accused of smuggling in the banned communications equipment.

U.S. officials said Gross was merely trying to help Cubans bypass the island's stringent restrictions on Internet access. But Cuban authorities say Gross was part of a plot to create "a Cuban spring" and destabilize the island's single-party communist government.

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CNN's Patrick Oppmann contributed to this report from Havana and CNN's Jamie Crawford contributed from Washington.