He said an American student at the time was instrumental in helping him smuggle the undeveloped roll of film past the huge security presence in the hotel lobby, and back to the Associated Press office to be sent around the world.
"Without his help, my picture would have never made it out."
Mr Widener believes the American student's name is either Kirk or Kurt - but he does not know for sure.
"I hope someday soon I can find him so I can thank him personally."
Mr Widener's photograph got him nominated as a finalist for a Pulitzer Prize in 1990.
Since then he has covered major stories in more than 100 countries and currently works as a photographer in Honolulu, Hawaii.
No-one knows for sure what happened to "tank man".
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