Christine Levinson's husband vanished while on a business trip to Iran. Five months later, she's going there to try to bring him back.

The mother of the couple's seven children is planning her own trip to Iran in search of husband Robert Levinson even though she's been advised by the State Department not to travel to Iran because of the risk.

"I am positive he is alive," Christine Levinson told The Associated Press in an interview Thursday from her home in Coral Springs, Fla. "If he were hospitalized or had been killed, we would have known by now."

The 6-foot-4 burly Levinson was last seen March 8 on Kish Island, a resort off the southern coast of Iran, where he had gone to seek information on cigarette smuggling for a client of his security firm.

His wife believes he remains in Iran because his name has not shown up on any flight manifests of planes leaving the country and his passport has not been used anywhere.

The Iranian government has denied any knowledge of Levinson despite repeated requests on his whereabouts by the State Department through Swiss intermediaries.

The Swiss Embassy in Iran agreed to pass along the requests because the United States and Iran do not have formal diplomatic ties.

State Department officials have cast doubt on Iran's claims that it knows nothing.

"We find it incredibly hard to believe their claims given the nature of their society and how they track people in their country," Tom Casey, deputy State Department spokesman, told the AP on Thursday.

Levinson last heard from her husband on March 8 just before he boarded a flight from Dubai in the United Arab Emirates to Iran's Kish Island.

A former FBI agent in New York and Florida who retired in 1998, Levinson usually called home twice a day and text-messaged his wife and the kids often from his cell phone on business trips.

When he did not call the next day, Christine Levinson called his cell phone and left a message on his voice mail, and then tried to reach him at his Dubai hotel room.

By the following day, she was worried. Levinson was scheduled to be in London but had not checked into his hotel. His business associates had not heard from him. It was his 59th birthday and he hadn't even called home.

The details of Levinson's trip to Kish remain murky. Levinson found out that her husband apparently met with Dawud Salahuddin, an American fugitive living in Iran who is wanted for the assassination of a former Iranian diplomat in Maryland in 1980.

Salahuddin has said that he was suddenly taken into custody by Iranian police while the two men were in a hotel lobby. Salahuddin said he was questioned about his documents. When he was released hours later, he returned to the hotel and discovered Levinson was gone.

No one has heard from Levinson since. Some speculate that his background as an FBI agent may have raised suspicion. The FBI said they have not had contact with Levinson since he retired.

His wife is now in the process of obtaining visas and making flight reservations to travel to Iran with her oldest son, 22-year-old Daniel, a law student. They hope to meet with authorities in Tehran and Kish.

"We keep praying," Christine Levinson said. "I tell my kids, `When dad comes home we want to make him proud of us. Keep looking forward.'"