An iconic photo of accused presidential assassin Lee Harvey Oswald was not faked as claimed by some, an American academic says.

Computer scientist Hany Farid at Dartmouth College digitally analyzed the picture with modern forensic tools and says it was not altered, the college announced Thursday.

The photo shows the alleged John F. Kennedy assassin in his Dallas back yard holding up both a rifle and Marxist literature. Oswald and others claimed the photo to be faked, citing inconsistent shadows and lighting.

"If we had found evidence of photo tampering, then it would have suggested a broader plot to kill JFK," Farid said. "Those who believe that there was a broader conspiracy can no longer point to this photo as possible evidence."

Federal officials determined long ago that the photo was not tampered with, Farid said, but many skeptics still claim there was a conspiracy.

A number of digital tools developed by Farid can determine whether photos have been changed, and are often used by law enforcement officials and in legal proceedings, Dartmouth officials said.