By Megan Cassella
WASHINGTON (Reuters) - The family of former FBI agent Robert Levinson, who went missing in Iran eight years ago, said on Tuesday it was "desperate for answers" on his whereabouts and expressed frustration at the information it had received from the Obama administration.
Levinson, who disappeared while visiting Iran's Kish Island in 2007, was not among the five American prisoners released by the Iranian government on Saturday as part of a prisoner swap with Washington.
His family said in a statement over the weekend it was "devastated," adding: "We are happy for the other families. But once again, Bob Levinson has been left behind."
In a speech on Sunday celebrating the release of the Americans, Obama said the U.S. government would "not rest" until Levinson was located. U.S. Secretary of State John Kerry said in a Twitter post on Sunday that Iran had agreed to deeper coordination to locate Levinson.
Levinson's son, Dan, told CNN on Tuesday the family "can only hope that they (U.S. officials) are really doing everything they can."
"President Obama has promised that, Secretary Kerry has promised that, but it hasn't ... given us results," Dan Levinson said. "We've been hearing this for years and years now," he said.
U.S. officials believe that Levinson, who suffered from diabetes, died in captivity after meeting with an American-born Islamic militant on Kish Island. Iranian officials have repeatedly denied knowledge of his disappearance or whereabouts.
Levinson's family has said he was working for the Central Intelligence Agency in what amounted to a rogue operation at the time he disappeared. The family's lawyer has told CNN the agency paid $2.5 million to avoid a lawsuit.
The CIA conducted an internal inquiry into Levinson's unauthorized relationship with the agency's analytical division, resulting in three officials being fired and several more being disciplined, officials have said.
Also speaking on CNN on Tuesday, Robert Levinson's wife, Christine, said she has tried to set up face-to-face meetings with high-level administration officials - including Obama, Kerry and U.S. National Security Advisor Susan Rice - to discuss her husband's case since November, but has been unsuccessful.
"We're desperate for answers, and we're really going to push hard, and we're not going to go away," Christine Levinson said.
She said the family had received one phone call from a member of the Obama administration after the American prisoners' release apologizing that they had not been warned ahead of time.
"Unfortunately we're still waiting for any information about Bob, and we need the United States government to work harder to bring him home," Christine Levinson told Fox News in a separate interview on Tuesday.
U.S. Deputy Secretary of State Antony Blinken said officials have been working to find Levinson and bring him back "the entire time."
"He's been absolutely part of everything we've tried to do," Blinken said separately on CNN, adding that the administration was uncertain Levinson was still being held in Iran.
The FBI has offered a reward of $5 million for information leading to Levinson's location and return.
(Editing by Susan Heavey and Paul Simao)