One year after former FBI agent Robert Levinson disappeared in Iran, the Iranian government still refuses to admit any knowledge of his whereabouts or fate.
Levinson went missing March 8, 2007, after arriving on the Iranian island of Kish.
Since then, the U.S. State Department says it has been stonewalled by Iran.
"We continue to press the Iranian government about Mr. Levinson and his whereabouts," State Department spokesman Tom Casey told ABC News. "We believe there is a lot more information out there and a lot more they could do to help find him."
According to associates, Levinson had traveled to Kish to meet with an American fugitive accused of murdering a former Iranian official in suburban Washington in 1980.
U.S. authorities say he was last seen after checking into a local hotel for the meeting.
A spokesman at the Iranian Mission in New York says authorities in Iran would like to be of more help, "but unfortunately nobody knows what happened."
His wife Christine traveled to Iran in December in an unsuccessful effort to turn up new information about her husband.
"I will never give up," she said.
She has now hired a lawyer in Iran to try to petition the government to fully investigate his disappearance.
At the same time, the FBI maintains it is committed to locating Levinson and bringing him home safely.
"The FBI is utilizing every resource possible and is working with numerous government agency partners to bring this investigation to a positive conclusion," Joseph Persichini, the assistant director in charge of the FBI's Washington field office, said.
A support rally for Levinson is planned in his hometown of Coral Springs, Fla., on Sunday.
Christine Levinson says her husband turns 60 on Monday.
"It's my hope that this rally will make people aware that Bob is still not home with us," she said.