The family of a retired FBI agent, who's been missing for five years, hopes a year-old videotape will rekindle the search for him.

Robert Levinson's wife and son believe he's being held captive in Iran.

They received a video message from him in November 2010. In the video, Levinson doesn't name his captors, but he does make a plea for help.

"And please help me get home. Thirty-three years of service to the United States deserves something. Please help me," he says on the tape.

"I have been treated well. But I need the help of the United States government to answer the requests of the group that has held me for three and a half years," Levinson says. "And please help me get home."

The family did not release the video until now because they feared it would jeopardize efforts to him bring home.

Despite a lengthy investigation, however, the U.S. government has no evidence of who is holding the 63-year-old father of seven.

"Please tell us your demands so we can work together to bring my father home safely," Levinson's son, David, said.

Levinson worked as a private investigator after retiring from the FBI. He traveled to Iran while working on a case in March 2007.

In the nearly five years that Levinson has been missing, the U.S. government has never had solid intelligence about what happened to him.