'I'll never stop looking for him,' wife of vanished ex-FBI agent says

(CNN) -- Christine Levinson went to the United Nations on Monday to ask questions about her husband, Bob, a former FBI agent who vanished in Iran last year.

Levinson flew to New York with three of her seven children in hopes of meeting the one man she hoped could really get things moving -- Iranian President Mahmoud Ahmadinejad, who is at the United Nations for a speech he is scheduled to deliver Tuesday afternoon.

Ahmadinejad declined to meet with her.

"I'm disappointed," she says.

Levinson did meet, however, with the Zalmay Khalilzad, the U.S. ambassador to the United Nations.

"He said he would do whatever he could to help me," she told CNN.

Levinson went to the United Nations with her children -- Susan, 31, Sarah, 28, and Douglas, 14. Her husband disappeared in March 2007 while on a business trip to the Iranian island of Kish.

Bob Levinson is a retired FBI agent from Coral Springs, Florida. After leaving the agency, his wife says, he worked as a security consultant specializing in cigarette smuggling.

Over the last year and half, Levinson says she has done everything she can to draw attention to her husband's disappearance.

She has given interviews, met with U.S. State Department officials, set up a Web site -- www.helpboblevinson.com -- and staged a rally. She even has offered a $5,000 reward, aimed primarily at Iranians who might have information about her husband.

Has it yielded any tips?

"No," Christine Levinson says. "Nothing."

Last year, she traveled to Iran to try to retrace her husband's steps. Back then, Iranian officials told her they would investigate and report back to her.

She says she hasn't heard a word.

"They told me when they have some information, they will let me know and in the meantime will continue to search for Bob," Levinson told CNN.

She has denied that her husband was doing business for the US government when he went missing -- she says she didn't believe so because he's a private citizen. And the State Department and FBI have denied he was working for government.

The State Department has demanded Iran free Levinson -- if it is holding him.

Levinson says her husband suffers from diabetes and high blood pressure.

She insists she is confident her husband is all right because "I haven't heard anything bad."

At times, she listens to his voicemail message, just to hear his voice.

"I still firmly believe he is alive," she says. "Every day, I tell my children to take things one day at a time.

"I just want him to know I'm still looking for him. I'll never stop looking for him."

All About Mahmoud Ahmadinejad • U.S. Department of State